I am a medical professional. But I am not clear about the case when someone wants to get postmortem done for his near or dear one, is it allowed even if doctors or administration does notsay so

If you mean a further autopsy because the family doesn't believe the cause of death, then yes, it is allowed and probaby will have to be paid for privately. Attending doctors, administration in the hospital, have their say, yes, but if the family wants confirmation they have the right to request it.

Maybe you could give more information than you have and that would administer a more appropriate Answer hsdarling.