Hi Joel,
1. Redefine your business process. In practice some companies put depot as plant for their convenience.
So think about your requirement if want to change or considering 650 plants for business use.
2. Give authorization only for superuser ( it depend on your requirement ) with a discipline practices
with the help froms basis guy.
3. Mr. Biju sir said was correct - create contract and adopt into PO w.r.t 650 plants.
Regards,
Vivek