Good Morning
In GST no centralised Registration like you have in service tax, under GST Act state centralised concept introduced I.e. In Maharashtra you have to take a single registration for all your branches and in other states you have to take separate registration same as in Maharashtra
Registration window will open On 27 June there you can take new registration
On gst.gov.in
After migration you have to file REG 25 form for Getting GST RC in this form you can add branches as additional place of business in same state (documents for proof same as you submit at the time of migration)
Procedure are almost same as done in migration form