diff --git a/python/ql/lib/semmle/python/frameworks/Django.qll b/python/ql/lib/semmle/python/frameworks/Django.qll
index 5f795bb0f40..ef5788b4b84 100644
--- a/python/ql/lib/semmle/python/frameworks/Django.qll
+++ b/python/ql/lib/semmle/python/frameworks/Django.qll
@@ -16,6 +16,7 @@ private import semmle.python.frameworks.internal.PoorMansFunctionResolution
 private import semmle.python.frameworks.internal.SelfRefMixin
 private import semmle.python.frameworks.internal.InstanceTaintStepsHelper
 private import semmle.python.security.dataflow.UrlRedirectCustomizations
+private import semmle.python.frameworks.data.ModelsAsData
 
 /**
  * INTERNAL: Do not use.
@@ -185,6 +186,10 @@ module Django {
         }
       }
 
+      private class MaDSubclass extends ModeledSubclass {
+        MaDSubclass() { this = ModelOutput::getATypeNode("django.forms.BaseForm~Subclass") }
+      }
+
       /** Gets a reference to the `django.forms.forms.BaseForm` class or any subclass. */
       API::Node subclassRef() { result = any(ModeledSubclass subclass).getASubclass*() }
     }
diff --git a/python/ql/lib/semmle/python/frameworks/FastApi.qll b/python/ql/lib/semmle/python/frameworks/FastApi.qll
index 0c4599d89ad..b39dd9ffd85 100644
--- a/python/ql/lib/semmle/python/frameworks/FastApi.qll
+++ b/python/ql/lib/semmle/python/frameworks/FastApi.qll
@@ -11,18 +11,21 @@ private import semmle.python.Concepts
 private import semmle.python.ApiGraphs
 private import semmle.python.frameworks.Pydantic
 private import semmle.python.frameworks.Starlette
+private import semmle.python.frameworks.data.ModelsAsData
 
 /**
  * Provides models for the `fastapi` PyPI package.
  * See https://fastapi.tiangolo.com/.
  */
-private module FastApi {
+module FastApi {
   /**
    * Provides models for FastAPI applications (an instance of `fastapi.FastAPI`).
    */
   module App {
+    API::Node cls() { result = API::moduleImport("fastapi").getMember("FastAPI") }
+
     /** Gets a reference to a FastAPI application (an instance of `fastapi.FastAPI`). */
-    API::Node instance() { result = API::moduleImport("fastapi").getMember("FastAPI").getReturn() }
+    API::Node instance() { result = cls().getReturn() }
   }
 
   /**
@@ -31,10 +34,14 @@ private module FastApi {
    * See https://fastapi.tiangolo.com/tutorial/bigger-applications/.
    */
   module ApiRouter {
-    /** Gets a reference to an instance of `fastapi.ApiRouter`. */
-    API::Node instance() {
-      result = API::moduleImport("fastapi").getMember("APIRouter").getASubclass*().getReturn()
+    API::Node cls() {
+      result = API::moduleImport("fastapi").getMember("APIRouter").getASubclass*()
+      or
+      result = ModelOutput::getATypeNode("fastapi.APIRouter~Subclass").getASubclass*()
     }
+
+    /** Gets a reference to an instance of `fastapi.ApiRouter`. */
+    API::Node instance() { result = cls().getReturn() }
   }
 
   // ---------------------------------------------------------------------------
diff --git a/python/ql/lib/semmle/python/frameworks/data/internal/empty.model.yml b/python/ql/lib/semmle/python/frameworks/data/internal/empty.model.yml
index 558f329ace8..4219c8ac175 100644
--- a/python/ql/lib/semmle/python/frameworks/data/internal/empty.model.yml
+++ b/python/ql/lib/semmle/python/frameworks/data/internal/empty.model.yml
@@ -30,6 +30,28 @@ extensions:
       - ["flask.MethodView~Subclass","flask_restplus","Member[resource].Member[MethodView]"]
       - ["flask.MethodView~Subclass","flask_restplus","Member[Resource]"]
 
+      - ["flask.MethodView~Subclass","flask_restx","Member[api].Member[SwaggerView]"]
+      - ["flask.MethodView~Subclass","flask_restx","Member[resource].Member[Resource]"]
+      - ["flask.MethodView~Subclass","flask_restx","Member[api].Member[Resource]"]
+      - ["flask.MethodView~Subclass","flask_restx","Member[resource].Member[MethodView]"]
+      - ["flask.MethodView~Subclass","flask_restx","Member[Resource]"]
+
+      - ["flask.MethodView~Subclass", "flask_restful", "Member[Resource]"]
+
+      - ["fastapi.APIRouter~Subclass","fastapi_utils","Member[inferring_router].Member[InferringRouter]"]
+      - ["fastapi.APIRouter~Subclass","fastapi_utils","Member[inferring_router].Member[APIRouter]"]
+      - ["fastapi.APIRouter~Subclass","fastapi_utils","Member[cbv].Member[APIRouter]"]
+
+      - ["django.forms.BaseForm~Subclass","haystack","Member[forms].Member[ModelSearchForm]"]
+      - ["django.forms.BaseForm~Subclass","haystack","Member[forms].Member[SearchForm]"]
+      - ["django.forms.BaseForm~Subclass","haystack","Member[forms].Member[FacetedSearchForm]"]
+      - ["django.forms.BaseForm~Subclass","haystack","Member[forms].Member[HighlightedSearchForm]"]
+      - ["django.forms.BaseForm~Subclass","haystack","Member[forms].Member[HighlightedModelSearchForm]"]
+      - ["django.forms.BaseForm~Subclass","haystack","Member[forms].Member[FacetedModelSearchForm]"]
+      - ["django.forms.BaseForm~Subclass","haystack","Member[views].Member[FacetedSearchForm]"]
+      - ["django.forms.BaseForm~Subclass","haystack","Member[views].Member[ModelSearchForm]"]
+
+
   - addsTo:
       pack: codeql/python-all
       extensible: typeVariableModel
diff --git a/python/ql/src/meta/ClassHierarchy/Find.ql b/python/ql/src/meta/ClassHierarchy/Find.ql
index 7067df844c1..fe6246e11eb 100644
--- a/python/ql/src/meta/ClassHierarchy/Find.ql
+++ b/python/ql/src/meta/ClassHierarchy/Find.ql
@@ -7,6 +7,14 @@ private import semmle.python.frameworks.FastApi
 private import semmle.python.frameworks.Django
 import semmle.python.frameworks.data.internal.ApiGraphModelsExtensions as Extensions
 
+// FIXME: I think the implementation below for `getAlreadyModeledClass` is wrong, since
+// it uses `.getASubclass*()` for flask/fastAPI (and initially also Django, I just fixed
+// it for django while discovering this problem). Basically, I fear that it if library
+// defines class A and B, where B is a subclass of A, the automated modeling might only
+// find B...
+//
+// I doesn't seem to be the case, which is probably why I didn't discover this, but on
+// top of my head I can't really tell why.
 class FlaskViewClasses extends FindSubclassesSpec {
   FlaskViewClasses() { this = "flask.View~Subclass" }
 
@@ -21,6 +29,36 @@ class FlaskMethodViewClasses extends FindSubclassesSpec {
   override FlaskViewClasses getSuperClass() { any() }
 }
 
+class FastApiRouter extends FindSubclassesSpec {
+  FastApiRouter() { this = "fastapi.APIRouter~Subclass" }
+
+  override API::Node getAlreadyModeledClass() { result = FastApi::ApiRouter::cls() }
+}
+
+class DjangoForms extends FindSubclassesSpec {
+  DjangoForms() { this = "django.forms.BaseForm~Subclass" }
+
+  override API::Node getAlreadyModeledClass() {
+    result = any(Django::Forms::Form::ModeledSubclass subclass)
+  }
+}
+
+class DjangoView extends FindSubclassesSpec {
+  DjangoView() { this = "Django.Views.View~Subclass" }
+
+  override API::Node getAlreadyModeledClass() {
+    result = any(Django::Views::View::ModeledSubclass subclass)
+  }
+}
+
+class DjangoField extends FindSubclassesSpec {
+  DjangoField() { this = "Django.Forms.Field~Subclass" }
+
+  override API::Node getAlreadyModeledClass() {
+    result = any(Django::Forms::Field::ModeledSubclass subclass)
+  }
+}
+
 bindingset[fullyQualified]
 predicate fullyQualifiedToYamlFormat(string fullyQualified, string type2, string path) {
   exists(int firstDot | firstDot = fullyQualified.indexOf(".", 0, 0) |