This discussion clarifies the documentation needed for GST registration when using a father's address. While an electricity bill for the premises is generally sufficient proof of address, a consent letter from the father is often required, especially if the bill is not in the applicant's name. Some users suggest the consent letter may need to be notarised or on stamp paper, though others have had success with simple A4 consent letters. Property tax receipts can also be used as an alternative document if needed.
And one more thing is important here as in case the person write expense "RENT PAID" in his books of accounts for the premises then it's problem in future his registration with IT...