The vendor does not exist on that item record and the users do not want to have to go to the item record to add it. So I created a column field that sources the master vendor list. So if this column list has a vendor selected, then the user gets a prompt on validate line if they would like to add this vendor. If they do, then it asks for purchase price and vendor code. Then it loads the item record and adds a new vendor. I cannot set it directly because at the time the PO Vendor list was sourced, this newly added vendor is not included.