Multiple business place

Dear Sir,

What are the document process of multiple business with one gst number ( same state ) under GST regime.

Example.

1) stock tranfer from A to B ( which type of  document )

2) From B to customer ( Tax Invoice with GST )

3) shall we tranfer the material from B to A (which type of  document)

4) raw material can be purchased in both the places in this case, what is the imapct of ITC

Thanks & Regards

Bhaskar