diff --git a/app/aidbox/operations.py b/app/aidbox/operations.py
index 04ac43f..cbc3420 100644
--- a/app/aidbox/operations.py
+++ b/app/aidbox/operations.py
@@ -2,7 +2,7 @@
 
 from aiohttp import web
 
-from app.converter import from_first_class_extension, to_first_class_extension
+from app.converter.aidbox import from_first_class_extension, to_first_class_extension
 
 from ..sdc import (
     assemble,
@@ -30,7 +30,9 @@ async def assemble_op(request: AidboxSdcRequest):
     assembled_questionnaire_lazy = await assemble(request.fhir_client, questionnaire)
     assembled_questionnaire = json.loads(json.dumps(assembled_questionnaire_lazy, default=list))
     if request.is_fhir:
-        assembled_questionnaire = from_first_class_extension(assembled_questionnaire)
+        assembled_questionnaire = await from_first_class_extension(
+            assembled_questionnaire, request.aidbox_client
+        )
     return web.json_response(assembled_questionnaire)
 
 
@@ -40,7 +42,9 @@ async def constraint_check_operation(request: AidboxSdcRequest):
     env = parameter_to_env(request.resource)
 
     questionnaire = (
-        to_first_class_extension(env["Questionnaire"]) if request.is_fhir else env["Questionnaire"]
+        await to_first_class_extension(env["Questionnaire"], request.aidbox_client)
+        if request.is_fhir
+        else env["Questionnaire"]
     )
     as_root = questionnaire.get("runOnBehalfOfRoot")
     client = client if as_root else get_user_sdk_client(request.request, request.client)
@@ -54,7 +58,9 @@ async def get_questionnaire_context_operation(request: AidboxSdcRequest):
     env = parameter_to_env(request.resource)
 
     questionnaire = (
-        to_first_class_extension(env["Questionnaire"]) if request.is_fhir else env["Questionnaire"]
+        await to_first_class_extension(env["Questionnaire"], request.aidbox_client)
+        if request.is_fhir
+        else env["Questionnaire"]
     )
     as_root = questionnaire.get("runOnBehalfOfRoot")
     client = client if as_root else get_user_sdk_client(request.request, request.client)
@@ -81,7 +87,7 @@ async def extract_questionnaire_operation(request: AidboxSdcRequest):
     elif resource["resourceType"] == "Parameters":
         env = parameter_to_env(request.resource)
         questionnaire = (
-            to_first_class_extension(env["Questionnaire"])
+            await to_first_class_extension(env["Questionnaire"], request.aidbox_client)
             if request.is_fhir
             else env["Questionnaire"]
         )
@@ -147,14 +153,18 @@ async def populate_questionnaire(request: AidboxSdcRequest):
         )
 
     questionnaire = (
-        to_first_class_extension(env["Questionnaire"]) if request.is_fhir else env["Questionnaire"]
+        await to_first_class_extension(env["Questionnaire"], request.aidbox_client)
+        if request.is_fhir
+        else env["Questionnaire"]
     )
     as_root = questionnaire.get("runOnBehalfOfRoot")
     client = request.client if as_root else get_user_sdk_client(request.request, request.client)
 
     populated_resource = await populate(client, questionnaire, env)
     if request.is_fhir:
-        populated_resource = from_first_class_extension(populated_resource)
+        populated_resource = await from_first_class_extension(
+            populated_resource, request.aidbox_client
+        )
     return web.json_response(populated_resource)
 
 
@@ -172,7 +182,9 @@ async def populate_questionnaire_instance(request: AidboxSdcRequest):
 
     populated_resource = await populate(client, questionnaire, env)
     if request.is_fhir:
-        populated_resource = from_first_class_extension(populated_resource)
+        populated_resource = await from_first_class_extension(
+            populated_resource, request.aidbox_client
+        )
     return web.json_response(populated_resource)
 
 
diff --git a/app/converter/aidbox.py b/app/converter/aidbox.py
new file mode 100644
index 0000000..f2c5258
--- /dev/null
+++ b/app/converter/aidbox.py
@@ -0,0 +1,12 @@
+async def from_first_class_extension(fce_resource, aidbox_client):
+    fhir_resource = await aidbox_client.execute(
+        "/$to-format/fhir", method="post", data=fce_resource, params=None
+    )
+    return fhir_resource.get("resource")
+
+
+async def to_first_class_extension(fhir_resource, aidbox_client):
+    fce_resource = await aidbox_client.execute(
+        "/$to-format/aidbox", method="post", data=fhir_resource, params=None
+    )
+    return fce_resource.get("resource")
diff --git a/tests/sdc/test_assemble.py b/tests/sdc/test_assemble.py
index 3ee6127..701f1ca 100644
--- a/tests/sdc/test_assemble.py
+++ b/tests/sdc/test_assemble.py
@@ -552,6 +552,14 @@ async def test_assemble_sub_questionnaire_fhir(aidbox_client, safe_db):
         "status": "active",
         "resourceType": "Questionnaire",
         "extension": [
+            {
+                "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-targetStructureMap",
+                "valueCanonical": "StructureMap/create-another-patient",
+            },
+            {
+                "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-targetStructureMap",
+                "valueCanonical": "StructureMap/create-patient",
+            },
             {
                 "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-launchContext",
                 "extension": [
@@ -560,23 +568,17 @@ async def test_assemble_sub_questionnaire_fhir(aidbox_client, safe_db):
                         "valueCoding": {
                             "system": "http://hl7.org/fhir/uv/sdc/CodeSystem/launchContext",
                             "code": "LaunchPatient",
-                            "system": "http://hl7.org/fhir/uv/sdc/CodeSystem/launchContext",
                         },
                     },
-                    {"url": "type", "valueCode": "Patient"},
+                    {
+                        "url": "type",
+                        "valueCode": "Patient",
+                    },
                 ],
             },
             {
-                "url": "https://jira.hl7.org/browse/FHIR-22356#assembledFrom",
-                "valueCanonical": q.id,
-            },
-            {
-                "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-targetStructureMap",
-                "valueCanonical": "StructureMap/create-another-patient",
-            },
-            {
-                "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-targetStructureMap",
-                "valueCanonical": "StructureMap/create-patient",
+                "url": "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-assembledFrom",
+                 "valueCanonical": q['id']
             },
         ],
     }