AP - 3 way PO needs a Vouchermatch to set it auto paid

3 way PO needs a receiving, and when they do a voucher match they would have to enter a 4 type to enter a negative line inorder to offset this PO to 0 as PO is created for tracking purposes. I tried to set the Processing option to 'P' and when you do a voucher match it displays an error AP Status Error you cannot set it to P, # etc.... How can we handle PO where we need the receiving but do not want to do any invoicing, and not stay in RNV