Dear Sir,
GST is a PAN based registration. In case of sole-proprietorship GST registration, you need to obtain the PAN of an Individual. For obtaining PAN you can apply online on TIN website.
For GST registration you will require the below docs at the time of registration.
1) One coloured photograph.
2) Copy of cancelled cheque/first page of pass book/bank statement
3) Rent agreement if premises rented or property tax receipt/electricity bill if owned. In your case, if the office space belongs to any one of your individual you need consent letter of the individual who owned the house alongwith any of the above supporting docs.
4) Legally current account is mandatory as saving accounts are for individual only. It is advisable to open current account first and then apply for GST registration if there is no hurry.
5) At the time of registration it will ask legal name and trade name. Mention name of individual on whose PAN GST registration will be obtained and name of business under Trade Name.
Note: Please fill all the details carefully to avoid delay in issuing of GSTN.
Thanks