Dynamically Changing Value List Questions

Is there any way to use different value lists for the same field (on the same layout) under different circumstances?

I need to pull up a pop-up list of Contact ID's for correspondence. If the correspondence is outgoing, the From ID value list should be populated entirely by employees (gathered from a related table). If the correspondence is incoming, it should be populated by everyone else (gathered from the same related table as the employees). When I try to do it using "related values only" the short employee list pops up rather quickly. But the longer list of everyone else almost never pops up and sometimes causes FM to freeze.

I've also tried passing value lists through to fields (Get Value List Items) in order to use a calculation to create new value lists. But because I want two columns (Contact ID and Contact Name) it doesn't work.

Is there a better solution? Does anyone have a suggestion? I'm trying to avoid using multiple layouts because it will just generate extra navigational scripting in the end.

On a related note, Pop-up lists in FM7 can be sorted by the second field as in FM6. But when you go to enter a record and try to select them from the keyboard, the first value is selected, not the second (unlike FM6). This STINKS! Any insight?

Thanks