Please HELP -- Need a two-way value list solution

[zincb]

(Filemaker 6)

We have a "Clients.fp5" file, and it has a "Client Name" and a "Client ID" field (along with lots of other Client information).

In a different file, the user wants to be able to type in a Client ID, and have all the other information, including Client Name, be looked up.

If they don't know the Client ID, they want to be able to select from a dropdown list of Client Names, and have all the other Client information, including Client ID, be looked up.

The only solution I can think of is a complicated one that I don't want to saddle them with, after I am gone.

Does anyone have a simple way of doing this?