Problem not fixed after all. I still get system crashes if I sort the list on the list page, change to Properties page, navigate to required parent, change a parent field and Save. Profile shows the parent being updated correctly but then another update to a child record using a totally different foreign key (not the one from the parent just saved). It seemed to be working if I only hit the column header once for sorting but if I sort in descending order (by clicking twice), I got the error again. The update does not even hit the code in the business rules object for the child table.