Fix issue with diagram tool auto redrawing relationship lines when tables are dropped and recreated with no changes to relationships from old to new tables.

Specifically I reverse engineered my tables into the database diagraming tool. Then painstakingly organized the tables then adjusted all the relationship lines so they take a short path and do not cross then saved the diagram.

When re-opening it everything is fine. But - if I ever drop and recreate the tables (e.g. with a script to change the schema) the diagram tool auto-redraws all the relationships and the diagram becomes a mess.

Please fix. This is a show-stopper for me using the diagraming tool.