Bill To purchase orders or prevent change orders to send to suppliers

Summary:

Prevent sending POs to suppliers for Bill-To purchase orders or change order initiated at the requisition

Content (required):

Anyone have a solution/workaround for:

1) A bill-to purchase order, short of creating a supplier site that has no communication method?

2) A change order that is initiated by the requester on a requisition that will not send to the supplier to potentially increase/ decrease qty to facilitate invoice