How: re-import deleted table association

[CJ]

G'day folks,

While working on logical diagrams with imported database tables, I unintentionally deleted an association between two tables.  How can I get that association back without having to manually recreate it?

I've tried importing the DDL schema again, with "synchronize existing classes" option set, but that didn't bring the association back (I tried synchronizing for just the two tables, and for all tables).

Thanks in advance, and best regards.