Esic and health insurance data

When we are adding employees to the HR module, we are not able to add and details of help insurance like insurance policy no and we are not able to find any option for the ESIC, in that doc type there is only one provision for adding insurance provider name only apart from that nothing else we can add to it.

When I want to edit that doc type I can across the employee health insurance doctpye is noneditable doc type

Please help me to add those functions to this doctype as we have to submit data to government these are some crucial information date that government needs for clearance of our bill

It can be done using Customization.