Need API to update payment terms only for open PO

I have a  requests to modify payment terms on open Purchase Orders (POs) for certain suppliers, which results in a lot of manual effort by the Buyers, to make these changes. Is there some way that this can be accomplished systematically?

Followed the metalink: Doc ID 1505147.1 for the same but it seems its updating lines, shipment and distributions details.

can we use API:PO_DOCUMENT_UPDATE_GRP.UPDATE_DOCUMENT() to accomplish the same.?

If so, then how to pass on Term _id in that.

Is there any method available to set term_id details at header level.
I just wanted to change Payment term based on PO No and buyer id provided as inputs.