What exactly is the end goal of merging the lists Jack?
It's not that hard to use a table with the list, and include a Value List designation field, something like a category tag or something to distinguish the record as belonging a specific "list". Then you can pull in only the values you need for a specific use-case.
Using a Virtual List can also a good option. http://www.modularfilemaker.org/module/virtual-value-list/
I think you need a table that has every value per record (not one record, one field) to avoid sorting the values by itself.
Kinda guessing here, but your predicament might be a clue that your UI is going to be unclear. In your case, it looks like you're using one UI element to control two different ideas, namely both "done or undone" and "when [is | was] it [due | done]". There may or may not be good reasons for doing it this way, so I don't mean to go all "that's not what you want to do," but I often find that when I'm straining to make the UI behave, it is easier on me and on the user to take a different approach. Maybe you could show only undone items by default, for example, and add a single button to "turn on" the completed items. Then your date range menu only has to worry about Overdue, Today, and Upcoming. Completed items really only have a completion date anyway, so the date range menu wouldn't necessarily apply.
In any case, if you were to proceed with your approach, your idea is as good as anything I'd come up with. I'd probably use a global field on the table with the kind of calculation you describe, something like filterStatusList [ Calculation ; ListA & ¶ & ListB ].