Ok Wow. Lets all calm down. I spoke to the Service tax department in Mumbai and got my query solved. Since the change is only in the name and since its a sole proprietorship firm and NOT a partnership firm or a LLP or a company, I dont have to submit any other document apart from the amended ST1 and the original ST2. This is beacuse my PAN number and Address remains the same.
Anyway, thanks for your inputs guys. Appreciate it!