diff --git a/README.md b/README.md
index c0111d3..bb6880d 100644
--- a/README.md
+++ b/README.md
@@ -159,3 +159,9 @@ Here are some performance metrics for the above query for the small test sqlite
 #### Nested fields and wildcards are not supported / tested
 
 `can('read', 'User', ['nested.field', 'field.*'])` probably won't work.
+
+#### Combined relation fields are not supported
+
+`entry Relation @relation(fields: [entryIdA, entryIdB], references: [refA, refB])` does not work.
+`entry Relation @relation(fields: [entryId], references: [ref])` does work.
+Since internally a relation like `entryId: someId` might be replaced by `entry: { connect: { ref: someId, ...caslConditions } }`
diff --git a/src/applyCaslToQuery.ts b/src/applyCaslToQuery.ts
index a7bde98..f798cee 100644
--- a/src/applyCaslToQuery.ts
+++ b/src/applyCaslToQuery.ts
@@ -6,6 +6,7 @@ import { applyIncludeSelectQuery } from "./applyIncludeSelectQuery"
 import { applyRuleRelationsQuery } from './applyRuleRelationsQuery'
 import { applyWhereQuery } from "./applyWhereQuery"
 import { caslOperationDict, PrismaCaslOperation } from "./helpers"
+import { transformDataToWhereQuery } from "./transformDataToWhereQuery"
 
 /**
  * Applies CASL authorization logic to prisma query
@@ -26,6 +27,9 @@ export function applyCaslToQuery(operation: PrismaCaslOperation, args: any, abil
         const { args: dataArgs, creationTree: dataCreationTree } = applyDataQuery(abilities, args.data, operationAbility.action, model)
         creationTree = dataCreationTree
         args.data = dataArgs
+        if (operation === 'updateMany') {
+            args = transformDataToWhereQuery(args, model)
+        }
     }
 
 
diff --git a/src/transformDataToWhereQuery.ts b/src/transformDataToWhereQuery.ts
new file mode 100644
index 0000000..4034193
--- /dev/null
+++ b/src/transformDataToWhereQuery.ts
@@ -0,0 +1,33 @@
+import { relationFieldsByModel } from "./helpers"
+
+export function transformDataToWhereQuery(args: any, model: string) {
+
+  ;['connect', 'disconnect'].forEach((action) => {
+    Object.entries(args.data).forEach(([relation, obj]: [string, any]) => {
+      if (typeof obj === 'object' && !Array.isArray(obj) && obj[action]) {
+        // combine args.data.relation[action].AND and args.where.AND
+        const ANDArgs = { AND: [...(obj[action].AND ?? []), ...(args.where[relation]?.AND ?? [])] }
+        const relationTo = relationFieldsByModel[model][relation].relationToFields?.[0]
+        const relationFrom = relationFieldsByModel[model][relation].relationFromFields?.[0]
+        if (!relationTo || !relationFrom) {
+          throw new Error('Cannot find correct relations to transform updateMany to casl query.')
+        }
+        args.where = {
+          ...(args.where ?? {}),
+          [relation]: {
+            ...(args.where[relation] ?? {}),
+            ...obj[action],
+            ...(ANDArgs.AND.length > 0 ? ANDArgs : {})
+          }
+        }
+        args.data = {
+          ...args.data,
+          [relationFrom]: obj[action][relationTo]
+        }
+        delete args.data[relation]
+        delete args.where[relation][relationTo]
+      }
+    })
+  })
+  return args
+}
\ No newline at end of file
diff --git a/test/transformDataToWhereQuery.test.ts b/test/transformDataToWhereQuery.test.ts
new file mode 100644
index 0000000..a88257a
--- /dev/null
+++ b/test/transformDataToWhereQuery.test.ts
@@ -0,0 +1,21 @@
+import { transformDataToWhereQuery } from '../src/transformDataToWhereQuery'
+
+describe('transform data to where query', () => {
+
+  it('converts data relations with connect to where query and transforms to relationField data entries', () => {
+
+    const result = transformDataToWhereQuery({ data: { id: 1, thread: { connect: { id: 0, text: 'a' } } }, where: { id: 0 } },
+      'Post'
+    )
+    expect(result.data).toEqual({ id: 1, threadId: 0 })
+    expect(result.where).toEqual({ id: 0, thread: { text: 'a' } })
+  })
+
+  it('converts data relations with disconnect to where query and transforms to relationField data entries', () => {
+    const result = transformDataToWhereQuery({ data: { id: 1, thread: { disconnect: { id: 0, text: 'a' } } }, where: { id: 0 } },
+      'Post'
+    )
+    expect(result.data).toEqual({ id: 1, threadId: 0 })
+    expect(result.where).toEqual({ id: 0, thread: { text: 'a' } })
+  })
+})