How can the payment currency field on the invoice generated from the suppliers Portal be editable

Summary: How can the payment currency field on the invoice generated from the suppliers portal be editable as the user doesn't want to assign a default payment currency to the suppliers but wants to be able to change the payment currency. the payment currency field is greyed out

Content (required): Its noticed that its a seeded functionality in oracle fusion that suppliers cannot change payment currency but users wants that when the invoice becomes available in an editable mode in the payable module, they should be able to edit/change payment currency.

I would appreciate it if there is a workaround as to this regard.