diff --git a/.changeset/khaki-mayflies-float.md b/.changeset/khaki-mayflies-float.md
new file mode 100644
index 0000000000..30767d67fa
--- /dev/null
+++ b/.changeset/khaki-mayflies-float.md
@@ -0,0 +1,6 @@
+---
+"@neo4j/graphql": major
+"@neo4j/graphql-ogm": major
+---
+
+The Neo4j GraphQL Library now only accepts a `string`, `DocumentNode` or an array containing these types. A callback function returning these is also accepted. This is a reduction from `TypeSource` which also included types such as `GraphQLSchema` and `DefinitionNode`, which would have resulted in unexpected behaviour if passed in.
diff --git a/packages/graphql/src/classes/Neo4jGraphQL.ts b/packages/graphql/src/classes/Neo4jGraphQL.ts
index b33ada341a..5bc58aee1d 100644
--- a/packages/graphql/src/classes/Neo4jGraphQL.ts
+++ b/packages/graphql/src/classes/Neo4jGraphQL.ts
@@ -40,7 +40,6 @@ import type { Neo4jGraphQLSchemaModel } from "../schema-model/Neo4jGraphQLSchema
 import { composeResolvers } from "@graphql-tools/resolvers-composition";
 import type { IExecutableSchemaDefinition } from "@graphql-tools/schema";
 import { addResolversToSchema, makeExecutableSchema } from "@graphql-tools/schema";
-import type { TypeSource } from "@graphql-tools/utils";
 import { forEachField, getResolversFromSchema } from "@graphql-tools/utils";
 import type { DocumentNode, GraphQLSchema } from "graphql";
 import type { Driver, SessionConfig } from "neo4j-driver";
@@ -50,8 +49,10 @@ import { makeDocumentToAugment } from "../schema/make-document-to-augment";
 import { Neo4jGraphQLAuthorization } from "./authorization/Neo4jGraphQLAuthorization";
 import { Neo4jGraphQLSubscriptionsDefaultEngine } from "./Neo4jGraphQLSubscriptionsDefaultEngine";
 
+type TypeDefinitions = string | DocumentNode | TypeDefinitions[] | (() => TypeDefinitions);
+
 export interface Neo4jGraphQLConstructor {
-    typeDefs: TypeSource;
+    typeDefs: TypeDefinitions;
     resolvers?: IExecutableSchemaDefinition["resolvers"];
     features?: Neo4jFeaturesSettings;
     driver?: Driver;
@@ -60,7 +61,7 @@ export interface Neo4jGraphQLConstructor {
 }
 
 class Neo4jGraphQL {
-    private typeDefs: TypeSource;
+    private typeDefs: TypeDefinitions;
     private resolvers?: IExecutableSchemaDefinition["resolvers"];
 
     private driver?: Driver;
@@ -208,6 +209,39 @@ class Neo4jGraphQL {
         return this._relationships;
     }
 
+    /**
+     * Currently just merges all type definitions into a document. Eventual intention described below:
+     *
+     * Normalizes the user's type definitions using the method with the lowest risk of side effects:
+     * - Type definitions of type `string` are parsed using the `parse` function from the reference GraphQL implementation.
+     * - Type definitions of type `DocumentNode` are returned as they are.
+     * - Type definitions in arrays are merged using `mergeTypeDefs` from `@graphql-tools/merge`.
+     * - Callbacks are resolved to a type which can be parsed into a document.
+     *
+     * This method maps to the Type Definition Normalization stage of the Schema Generation lifecycle.
+     *
+     * @param {TypeDefinitions} typeDefinitions - The unnormalized type definitions.
+     * @returns {DocumentNode} The normalized type definitons as a document.
+     */
+    private normalizeTypeDefinitions(typeDefinitions: TypeDefinitions): DocumentNode {
+        // TODO: The dream: minimal modification of the type definitions. However, this does not merge extensions, which we can't currently deal with in translation.
+        // if (typeof typeDefinitions === "function") {
+        //     return this.normalizeTypeDefinitions(typeDefinitions());
+        // }
+
+        // if (typeof typeDefinitions === "string") {
+        //     return parse(typeDefinitions);
+        // }
+
+        // if (Array.isArray(typeDefinitions)) {
+        //     return mergeTypeDefs(typeDefinitions);
+        // }
+
+        // return typeDefinitions;
+
+        return mergeTypeDefs(typeDefinitions);
+    }
+
     private addDefaultFieldResolvers(schema: GraphQLSchema): GraphQLSchema {
         forEachField(schema, (field) => {
             if (!field.resolve) {
@@ -228,10 +262,6 @@ class Neo4jGraphQL {
         }
     }
 
-    private getDocument(typeDefs: TypeSource): DocumentNode {
-        return mergeTypeDefs(typeDefs);
-    }
-
     private async getNeo4jDatabaseInfo(driver: Driver, sessionConfig?: SessionConfig): Promise<Neo4jDatabaseInfo> {
         const executorConstructorParam: ExecutorConstructorParam = {
             executionContext: driver,
@@ -310,7 +340,7 @@ class Neo4jGraphQL {
 
     private generateExecutableSchema(): Promise<GraphQLSchema> {
         return new Promise((resolve) => {
-            const initialDocument = this.getDocument(this.typeDefs);
+            const initialDocument = this.normalizeTypeDefinitions(this.typeDefs);
 
             if (this.validate) {
                 validateDocument({ document: initialDocument, features: this.features });
@@ -350,7 +380,7 @@ class Neo4jGraphQL {
         // Import only when needed to avoid issues if GraphQL 15 being used
         const { Subgraph } = await import("./Subgraph");
 
-        const initialDocument = this.getDocument(this.typeDefs);
+        const initialDocument = this.normalizeTypeDefinitions(this.typeDefs);
         const subgraph = new Subgraph(this.typeDefs);
 
         const { directives, types } = subgraph.getValidationDefinitions();
diff --git a/packages/graphql/tests/e2e/federation/setup/subgraph.ts b/packages/graphql/tests/e2e/federation/setup/subgraph.ts
index 9a5141a27f..3c6563163a 100644
--- a/packages/graphql/tests/e2e/federation/setup/subgraph.ts
+++ b/packages/graphql/tests/e2e/federation/setup/subgraph.ts
@@ -17,15 +17,22 @@
  * limitations under the License.
  */
 
-import type { TypeSource } from "@graphql-tools/utils";
-import type { GraphQLSchema } from "graphql";
+import type { DocumentNode, GraphQLSchema } from "graphql";
 import type * as neo4j from "neo4j-driver";
 import { Neo4jGraphQL } from "../../../../src";
 
 export class TestSubgraph {
     library: Neo4jGraphQL;
 
-    constructor({ typeDefs, resolvers, driver }: { typeDefs: TypeSource; resolvers?: any; driver: neo4j.Driver }) {
+    constructor({
+        typeDefs,
+        resolvers,
+        driver,
+    }: {
+        typeDefs: string | DocumentNode;
+        resolvers?: any;
+        driver: neo4j.Driver;
+    }) {
         this.library = new Neo4jGraphQL({
             typeDefs,
             resolvers,