PO Document types with no association to a Vendor

Hi,

Customer is looking to convert their approved purchases into Purchasing module before go live.

The amounts are approved by FP&A at the GL Account level but they are not tied to any supplier.

Does Purchasing document types allow tracking these approved amounts as contract or blanket agreements? We are not associating a specific vendor to these pre-approved amounts.

When Invoice is received, user would like to release a portion of the approved amount, match it to AP Invoice.

Thanks for your help !

Siva.