Thanks Dharmakashi and Faisal.
My issue is resolved 
Previously I had added created attibutes in Context node BTAdminH and did the binding using relationship BTHeaderCustExt.Though fields were appearing on the webUI screen,I was facing the issue with saving the field values.
Now, I have created new Context node BTCustomerH as a dependent node of BTAdminH. After creation of Context node, all the methods are generated successfully. Nothing to change/enhance.
Regards,
Anand