W line type with no Partial Shipments

We want to put an entire SO on hold when we have a W line type using the Partial Shipment logic.  However, P4210 does not back order a W line type and will not put the order on a "PH" hold based on the W line type.  In other words, if all other "S" line type items are available, the order will not go on PH hold.  When the R42520 runs the W line type will back order, but the order is not placed on a PH hold.   If an "S" line type is not available, the order is placed on