Hi @PrashRV ,
What I have understood is you want some account attributes for update operation in your webservice connector. If this is the case you can follow this approach:
Parent Endpoint: First, retrieve the account details and map them in the response mapping.
Child Endpoint: Extract the values from the Parent response and pass them to the body.
See similar post here : Add/Remove Entitlement operation $plan placeholder issues
Another alternate solution could be to use a beforeOperation rule to set your request body with required attributes.
Please check below documentation examples are given:
Web Services Before Operation Rule (sailpoint.com)
IdentityNow Rule Guide - Web Services Before Operation Rule - Compass (sailpoint.com)
Web Services Before Operation Rule | SailPoint Developer Community