>You need two controls (e.g. dropdown lists) rather than one.
Not true. The UNION query would be the source for most things.
>Your equipment table needs to store the name of the location table, as well as the foreign key for that table as appropriate.
This, on the other hand, will talk me out of it. The alternative would be to ensure that keys in the one table were never the same as keys in the other. But, since I'm actually doing this in Access 97, it is simpler to use autonumber fields.
>Reports now need UNIONs.
That doesn't matter, but I'm already convinced anyway. I won't do it.