How to avoid nets being renamed during eco

I am importing logic into an existing design.  "Allow etch removal during ECO" is unchecked.  Some of the footprint geometries changed resulting in pins disconnecting from nets during the import.  When a net has both pins disconnected, it gets assigned to a "dummy" net or, if over a shape, gets assigned the net of that shape.  This results in a lot of work to delete and re-route these nets.  How can I prevent existing clines and vias from losing their net assignment so I can fix up the disconnections caused by the change in footprint geometry?

Thanks.