diff --git a/packages/core/content-manager/server/tests/api/populate-dz.test.e2e.js b/packages/core/content-manager/server/tests/api/populate-dz.test.e2e.js
index 720e3c558b..fcf819bafc 100644
--- a/packages/core/content-manager/server/tests/api/populate-dz.test.e2e.js
+++ b/packages/core/content-manager/server/tests/api/populate-dz.test.e2e.js
@@ -157,9 +157,6 @@ describe('CM API - Populate dz', () => {
           __component: 'default.compo-a',
           items: {
             title: 'AAAA',
-            category: {
-              name: 'name',
-            },
           },
         },
         {
@@ -167,9 +164,6 @@ describe('CM API - Populate dz', () => {
           items: {
             name: 'BBBB',
             category: 'smthg',
-            category_diff: {
-              name: 'name',
-            },
           },
         },
       ],
diff --git a/packages/core/content-manager/server/tests/index.test.e2e.js b/packages/core/content-manager/server/tests/index.test.e2e.js
index 73cbf75e32..7497f69bd9 100644
--- a/packages/core/content-manager/server/tests/index.test.e2e.js
+++ b/packages/core/content-manager/server/tests/index.test.e2e.js
@@ -1,6 +1,7 @@
 'use strict';
 
-// Helpers.
+const { isEmpty } = require('lodash/fp');
+
 const { createTestBuilder } = require('../../../../../test/helpers/builder');
 const { createStrapiInstance } = require('../../../../../test/helpers/strapi');
 const form = require('../../../../../test/helpers/generators');
@@ -16,6 +17,14 @@ let strapi;
 let data;
 let rq;
 
+const getRelations = async (modelName, field, id) => {
+  const res = await rq({
+    method: 'GET',
+    url: `/content-manager/collection-types/api::${modelName}.${modelName}/${id}/${field}`,
+  });
+  return res.body.results || res.body;
+};
+
 const deleteFixtures = async () => {
   for (const [name, modelName] of [
     ['references', 'reference'],
@@ -80,7 +89,6 @@ describe('Relations', () => {
       data.tags.push(body);
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.articles)).toBeTruthy();
       expect(body.name).toBe('tag1');
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
@@ -109,7 +117,6 @@ describe('Relations', () => {
       data.tags.push(body);
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.articles)).toBeTruthy();
       expect(body.name).toBe('tag2');
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
@@ -138,7 +145,6 @@ describe('Relations', () => {
       data.tags.push(body);
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.articles)).toBeTruthy();
       expect(body.name).toBe('tag3');
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
@@ -173,8 +179,6 @@ describe('Relations', () => {
       expect(body.id).toBeDefined();
       expect(body.title).toBe(entry.title);
       expect(body.content).toBe(entry.content);
-      expect(Array.isArray(body.tags)).toBeTruthy();
-      expect(body.tags.length).toBe(0);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -188,6 +192,9 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(0);
     });
 
     test('Create article2 with tag1', async () => {
@@ -208,9 +215,6 @@ describe('Relations', () => {
       expect(body.id).toBeDefined();
       expect(body.title).toBe(entry.title);
       expect(body.content).toBe(entry.content);
-      expect(Array.isArray(body.tags)).toBeTruthy();
-      expect(body.tags.length).toBe(1);
-      expect(body.tags[0].id).toBe(data.tags[0].id);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -224,6 +228,10 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(1);
+      expect(tags[0].id).toBe(data.tags[0].id);
     });
 
     test('Update article1 add tag2', async () => {
@@ -242,9 +250,6 @@ describe('Relations', () => {
       expect(body.id).toBeDefined();
       expect(body.title).toBe(entry.title);
       expect(body.content).toBe(entry.content);
-      expect(Array.isArray(body.tags)).toBeTruthy();
-      expect(body.tags.length).toBe(1);
-      expect(body.tags[0].id).toBe(data.tags[1].id);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -258,30 +263,24 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(1);
+      expect(tags[0].id).toBe(data.tags[1].id);
     });
 
     test('Update article1 add tag1 and tag3', async () => {
-      const entry = { ...data.articles[0] };
-      entry.tags = entry.tags.map((tag) => tag.id);
-
-      entry.tags.push(data.tags[0].id);
-      entry.tags.push(data.tags[2].id);
-
-      cleanDate(entry);
-
       const { body } = await rq({
-        url: `/content-manager/collection-types/api::article.article/${entry.id}`,
+        url: `/content-manager/collection-types/api::article.article/${data.articles[0].id}`,
         method: 'PUT',
-        body: entry,
+        body: {
+          tags: [data.tags[0].id, data.tags[1].id, data.tags[2].id],
+        },
       });
 
-      data.articles[0] = body;
-
       expect(body.id).toBeDefined();
-      expect(body.title).toBe(entry.title);
-      expect(body.content).toBe(entry.content);
-      expect(Array.isArray(body.tags)).toBeTruthy();
-      expect(body.tags.length).toBe(3);
+      expect(body.title).toBe(data.articles[0].title);
+      expect(body.content).toBe(data.articles[0].content);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -295,27 +294,23 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(3);
     });
 
     test('Update article1 remove one tag', async () => {
-      const entry = { ...data.articles[0] };
-      entry.tags = entry.tags.slice(1).map((tag) => tag.id);
-
-      cleanDate(entry);
-
       const { body } = await rq({
-        url: `/content-manager/collection-types/api::article.article/${entry.id}`,
+        url: `/content-manager/collection-types/api::article.article/${data.articles[0].id}`,
         method: 'PUT',
-        body: entry,
+        body: {
+          tags: [data.tags[1].id, data.tags[2].id],
+        },
       });
 
-      data.articles[0] = body;
-
       expect(body.id).toBeDefined();
-      expect(body.title).toBe(entry.title);
-      expect(body.content).toBe(entry.content);
-      expect(Array.isArray(body.tags)).toBeTruthy();
-      expect(body.tags.length).toBe(2);
+      expect(body.title).toBe(data.articles[0].title);
+      expect(body.content).toBe(data.articles[0].content);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -329,6 +324,9 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(2);
     });
 
     test('Update article1 remove all tag', async () => {
@@ -347,8 +345,6 @@ describe('Relations', () => {
       expect(body.id).toBeDefined();
       expect(body.title).toBe(entry.title);
       expect(body.content).toBe(entry.content);
-      expect(Array.isArray(body.tags)).toBeTruthy();
-      expect(body.tags.length).toBe(0);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -362,6 +358,9 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(0);
     });
 
     test('Delete all articles should remove the association in each tags related to them', async () => {
@@ -398,13 +397,6 @@ describe('Relations', () => {
         },
       });
 
-      const articles = [article12, article13];
-
-      expect(Array.isArray(articles[0].tags)).toBeTruthy();
-      expect(articles[0].tags.length).toBe(1);
-      expect(Array.isArray(articles[1].tags)).toBeTruthy();
-      expect(articles[1].tags.length).toBe(1);
-
       const { body: foundTag } = await rq({
         url: `/content-manager/collection-types/api::tag.tag/${createdTag.id}`,
         method: 'GET',
@@ -416,7 +408,7 @@ describe('Relations', () => {
         url: '/content-manager/collection-types/api::article.article/actions/bulkDelete',
         method: 'POST',
         body: {
-          ids: articles.map((article) => article.id),
+          ids: [article12.id, article13.id],
         },
       });
 
@@ -465,9 +457,6 @@ describe('Relations', () => {
       data.articlesWithTag.push(body);
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.tags)).toBeTruthy();
-      expect(body.tags.length).toBe(1);
-      expect(body.tags[0].id).toBe(data.tags[0].id);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -480,6 +469,10 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+
+      const tags = await getRelations('articlewithtag', 'tags', body.id);
+      expect(tags.length).toBe(1);
+      expect(tags[0].id).toBe(data.tags[0].id);
     });
   });
 
@@ -507,7 +500,6 @@ describe('Relations', () => {
       data.categories.push(body);
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.articles)).toBeTruthy();
       expect(body.name).toBe('cat1');
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
@@ -522,6 +514,9 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+
+      const articles = await getRelations('category', 'articles', body.id);
+      expect(articles.length).toBe(0);
     });
 
     test('Create cat2', async () => {
@@ -536,7 +531,6 @@ describe('Relations', () => {
       data.categories.push(body);
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.articles)).toBeTruthy();
       expect(body.name).toBe('cat2');
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
@@ -551,6 +545,8 @@ describe('Relations', () => {
         username: null,
       });
       expect(body.publishedAt).toBeUndefined();
+      const articles = await getRelations('category', 'articles', body.id);
+      expect(articles.length).toBe(0);
     });
 
     test('Create article1 with cat1', async () => {
@@ -571,8 +567,6 @@ describe('Relations', () => {
       expect(body.id).toBeDefined();
       expect(body.title).toBe(entry.title);
       expect(body.content).toBe(entry.content);
-      expect(body.category.name).toBe(data.categories[0].name);
-      expect(Array.isArray(body.tags)).toBeTruthy();
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -585,26 +579,29 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+      expect(body.publishedAt).toBeUndefined();
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(0);
+
+      const category = await getRelations('article', 'category', body.id);
+      expect(category.name).toBe(data.categories[0].name);
     });
 
     test('Update article1 with cat2', async () => {
-      const entry = { ...data.articles[0], category: data.categories[1].id };
-
-      cleanDate(entry);
-
       const { body } = await rq({
-        url: `/content-manager/collection-types/api::article.article/${entry.id}`,
+        url: `/content-manager/collection-types/api::article.article/${data.articles[0].id}`,
         method: 'PUT',
-        body: entry,
+        body: {
+          category: data.categories[1].id,
+        },
       });
 
       data.articles[0] = body;
 
       expect(body.id).toBeDefined();
-      expect(body.title).toBe(entry.title);
-      expect(body.content).toBe(entry.content);
-      expect(body.category.name).toBe(data.categories[1].name);
-      expect(Array.isArray(body.tags)).toBeTruthy();
+      expect(body.title).toBe(data.articles[0].title);
+      expect(body.content).toBe(data.articles[0].content);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -617,6 +614,12 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(0);
+
+      const category = await getRelations('article', 'category', body.id);
+      expect(category.name).toBe(data.categories[1].name);
     });
 
     test('Create article2', async () => {
@@ -636,7 +639,6 @@ describe('Relations', () => {
       expect(body.id).toBeDefined();
       expect(body.title).toBe(entry.title);
       expect(body.content).toBe(entry.content);
-      expect(Array.isArray(body.tags)).toBeTruthy();
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -649,26 +651,25 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(0);
     });
 
     test('Update article2 with cat2', async () => {
-      const entry = { ...data.articles[1], category: data.categories[1].id };
-
-      cleanDate(entry);
-
       const { body } = await rq({
-        url: `/content-manager/collection-types/api::article.article/${entry.id}`,
+        url: `/content-manager/collection-types/api::article.article/${data.articles[1].id}`,
         method: 'PUT',
-        body: entry,
+        body: {
+          category: data.categories[1].id,
+        },
       });
 
       data.articles[1] = body;
 
       expect(body.id).toBeDefined();
-      expect(body.title).toBe(entry.title);
-      expect(body.content).toBe(entry.content);
-      expect(body.category.name).toBe(data.categories[1].name);
-      expect(Array.isArray(body.tags)).toBeTruthy();
+      expect(body.title).toBe(data.articles[1].title);
+      expect(body.content).toBe(data.articles[1].content);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -681,27 +682,27 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+
+      const tags = await getRelations('article', 'tags', body.id);
+      expect(tags.length).toBe(0);
+
+      const category = await getRelations('article', 'category', body.id);
+      expect(category.name).toBe(data.categories[1].name);
     });
 
     test('Update cat1 with article1', async () => {
-      const entry = { ...data.categories[0] };
-      entry.articles = entry.articles.map((article) => article.id);
-      entry.articles.push(data.articles[0].id);
-
-      cleanDate(entry);
-
       const { body } = await rq({
-        url: `/content-manager/collection-types/api::category.category/${entry.id}`,
+        url: `/content-manager/collection-types/api::category.category/${data.categories[0].id}`,
         method: 'PUT',
-        body: entry,
+        body: {
+          articles: [data.articles[0].id],
+        },
       });
 
       data.categories[0] = body;
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.articles)).toBeTruthy();
-      expect(body.articles.length).toBe(1);
-      expect(body.name).toBe(entry.name);
+      expect(body.name).toBe(data.categories[0].name);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -714,6 +715,9 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+
+      const articles = await getRelations('category', 'articles', body.id);
+      expect(articles.length).toBe(1);
     });
 
     test('Create cat3 with article1', async () => {
@@ -731,8 +735,6 @@ describe('Relations', () => {
       data.categories.push(body);
 
       expect(body.id).toBeDefined();
-      expect(Array.isArray(body.articles)).toBeTruthy();
-      expect(body.articles.length).toBe(1);
       expect(body.name).toBe(entry.name);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
@@ -746,10 +748,12 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+
+      const articles = await getRelations('category', 'articles', body.id);
+      expect(articles.length).toBe(1);
     });
 
-    // TODO RELATIONS: reimplement following tests
-    test.skip('Get article1 with cat3', async () => {
+    test('Get article1 with cat3', async () => {
       const { body } = await rq({
         url: `/content-manager/collection-types/api::article.article/${data.articles[0].id}/category`,
         method: 'GET',
@@ -760,7 +764,7 @@ describe('Relations', () => {
       });
     });
 
-    test.skip('Get article2 with cat2', async () => {
+    test('Get article2 with cat2', async () => {
       const { body } = await rq({
         url: `/content-manager/collection-types/api::article.article/${data.articles[1].id}/category`,
         method: 'GET',
@@ -771,7 +775,7 @@ describe('Relations', () => {
       });
     });
 
-    test.skip('Get cat1 without relations', async () => {
+    test('Get cat1 without relations', async () => {
       const { body } = await rq({
         url: `/content-manager/collection-types/api::category.category/${data.categories[0].id}/articles`,
         method: 'GET',
@@ -788,7 +792,7 @@ describe('Relations', () => {
       });
     });
 
-    test.skip('Get cat2 with article2', async () => {
+    test('Get cat2 with article2', async () => {
       const { body } = await rq({
         url: `/content-manager/collection-types/api::category.category/${data.categories[1].id}/articles`,
         method: 'GET',
@@ -800,7 +804,7 @@ describe('Relations', () => {
       });
     });
 
-    test.skip('Get cat3 with article1', async () => {
+    test('Get cat3 with article1', async () => {
       const { body } = await rq({
         url: `/content-manager/collection-types/api::category.category/${data.categories[2].id}/articles`,
         method: 'GET',
@@ -885,22 +889,19 @@ describe('Relations', () => {
     });
 
     test('Update article1 with ref1', async () => {
-      const entry = { ...data.articles[0], reference: data.references[0].id };
-
-      cleanDate(entry);
-
       const { body } = await rq({
-        url: `/content-manager/collection-types/api::article.article/${entry.id}`,
+        url: `/content-manager/collection-types/api::article.article/${data.articles[0].id}`,
         method: 'PUT',
-        body: entry,
+        body: {
+          reference: data.references[0].id,
+        },
       });
 
       data.articles[0] = body;
 
       expect(body.id).toBeDefined();
-      expect(body.title).toBe(entry.title);
-      expect(body.content).toBe(entry.content);
-      expect(body.reference.id).toBe(entry.reference);
+      expect(body.title).toBe(data.articles[0].title);
+      expect(body.content).toBe(data.articles[0].content);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -913,6 +914,9 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+
+      const reference = await getRelations('article', 'reference', body.id);
+      expect(reference.id).toBe(data.references[0].id);
     });
 
     test('Create article2 with ref1', async () => {
@@ -933,7 +937,6 @@ describe('Relations', () => {
       expect(body.id).toBeDefined();
       expect(body.title).toBe(entry.title);
       expect(body.content).toBe(entry.content);
-      expect(body.reference.id).toBe(entry.reference);
       expect(body.createdBy).toMatchObject({
         firstname: 'admin',
         id: 1,
@@ -946,6 +949,8 @@ describe('Relations', () => {
         lastname: 'admin',
         username: null,
       });
+      const reference = await getRelations('article', 'reference', body.id);
+      expect(reference.id).toBe(data.references[0].id);
     });
   });
 
@@ -969,7 +974,9 @@ describe('Relations', () => {
       });
 
       expect(createdReference.id).toBeDefined();
-      expect(createdReference.tag.id).toBe(createdTag.id);
+
+      const tag = await getRelations('reference', 'tag', createdReference.id);
+      expect(tag.id).toBe(createdTag.id);
     });
 
     test('Detach Tag to a Reference', async () => {
@@ -990,7 +997,8 @@ describe('Relations', () => {
         },
       });
 
-      expect(createdReference.tag.id).toBe(createdTag.id);
+      let tag = await getRelations('reference', 'tag', createdReference.id);
+      expect(tag.id).toBe(createdTag.id);
 
       const { body: referenceToUpdate } = await rq({
         url: `/content-manager/collection-types/api::reference.reference/${createdReference.id}`,
@@ -1000,7 +1008,8 @@ describe('Relations', () => {
         },
       });
 
-      expect(referenceToUpdate.tag).toBe(null);
+      tag = await getRelations('reference', 'tag', referenceToUpdate.id);
+      expect(isEmpty(tag)).toBe(true);
     });
 
     test('Delete Tag so the relation in the Reference side should be removed', async () => {