Hi @sreya Kandala.

Which version of DX API v1 or v2 are you using ?

@sreya Kandala

1. In the header of Dev Studio, click Create > Data Model > Data Transform.
2. Name the transform AllowedStartingFields.
3. On the Definition tab of the data transform, clear the Call superclass data transform check box.
4. Add page list properties:
5. Add a row with the Append and Map to action

Please refer this documentation for more details: https://docs.pega.com/bundle/dx-api/page/platform/dx-api/adding-case-creation-fields-v2.html

@sreya Kandala

Nested page should be included in the target tag.

{   "pageInstructions": [     {       "instruction": "UPDATE",

     "target": "Page1.Customer",       "content": {         "pyFirstName": "Customer First Name"       }     }   ] }

@sreya Kandala

 Use the Create Case DX API by posting JSON where each single-value property is a plain field, a Page is a nested object, a Page List is an array of objects, and a Page Group is an object keyed by group name. Don’t wrap anything in pyWorkPage; send only your case data under “content”. Use exact property names from your data model, keep numbers/booleans as JSON types, and send dates/times in ISO-8601 (UTC if possible). Example: {"caseTypeID":"MyCo-Claims-Work-Claim","processID":"Create","content":{"ClaimId":"CLM-123","Insured":{"FirstName":"Ava","LastName":"Lee","Address":{"Line1":"10 Main St","City":"Austin","State":"TX"}},"Losses":[{"Date":"2025-09-01T14:30:00Z","Type":"Fire","Amount":15000.75},{"Date":"2025-09-05T09:00:00Z","Type":"Water","Amount":2200}],"Contacts":{"Primary":{"Name":"John Doe","Phone":"555-0100"},"Agent":{"Name":"M. Kim","Phone":"555-0200"}}}}. Here Insured is a Page, Address is a nested Page, Losses is a Page List, and Contacts is a Page Group with “Primary” and “Agent” keys. If you have reference properties, send their scalar keys (like IDs) rather than whole pages. Return fields you want back via fields query param or read them later with the Get Case DX API.