physical share certificates lost

Hi Members,

I am from Bangalore and have been getting some dividend ever quarter from various companies in form of cheque delivered at home. However, it is in the name of my father who has expired before converting these to demat. I do not know where the original documents are, it could have been lost during house transfer. How could i possibly get these shares allotted to my mother's name? Also are there any agencies that could help me with the same?

Thanks,
Kiran