OE Prepayment records not being deleted when related order/receipt is deleted

I'm doing some work importing orders from an external system and the order number is being supplied by the external system. When I have some things to adjust and need to reimport the order, I notice that deleting the order in Sage doesn't remove the related record from OEPPRE, nor does it get removed when deleting the prepayment record in the receipt batch.

Can I have a couple of you run this query to see if you have orphaned records, too?

select * from OEPPRE
where APPLYTO=4
and not exists(select ORDNUMBER from OEORDH where OEORDH.ORDNUMBER=DOCNUMBER)