PO delivery from multiple plant

HI All,

I have scenarion related to Intercompany STO, plant A (co-code A) will request material X from plant B (co.code-B) when plant B does not have stock the PO goes as unconfirmed, is it possible to check stock availability at plant B and deliver the stock from plant B if plant B has stock to deliver against the same PO.

here plant A is a receiving plant and plant B is a Vendor.

please inform what changes need to be done to PO and what settings/functionlaity to be used to achieve this.

thanks in advance, early response appreciated.