Query about of point of taxation in Inter-state Sale(IGST) in GST, where more than two parties(more than two states) involved

Dear Sir,

Kindly make me the concept clear about point of taxation inter-state transactions where more than 2 parties of their different respective states involved, covering 2 points:

i) Transfer of document of title of goods to notify party.

ii) Physical Transfer of goods to final destination as per notification.