Takeover of firm by company

yes firms identify is no more ad it gets merged with the company. Al. the assets/liabilities of the firm get transferred to the co at agreed values.
if any losses are there these will get transferred to the the co and the co will get tax benefit for c/f if losses transferred. similarly if any GST ITC is remaining the same will get transferred to the co

CAN YOU TELL WHAT IS THE PROCEDURE FOR STATING TAKEOVER 

I MEAN WHICH FORM TO FILE 

AND FIRM NEEDS TO BE DISSOLVED OR IT IS AUTOMATICALLY DISSOLVED