Sales Order Search - Exclude Orders with Open Drop Ship Lines

We have a transaction search to show our sales orders which have been partially fulfilled or are pending fulfillment. However, we have some orders showing up that have open drop ship lines associated with them when all other lines have been fulfilled. Please note that all of our items can potentially be drop shipped, so we can't just use Item: Drop Ship Item as a filter, since we sometimes drop ship items without drop ship checked on the item record. I've tried using Line System Notes, but that hasn't worked. Also used the suggested Purchase Order : Internal ID (Number)