Norrie,
Perhaps you need to use either groups or a mailing list manager to accomplish this.
With groups (a long winded way to accomplish what you want), you might create an account for each addresses to be forwarded to and set their mail to be forwarded to their actual e-mail address. Then in the multipop engine, specify the name of the group as the forwarding address. I haven't actually tried this out myself so I don't actually know the pitfalls .....
With a mailing list manager, you could set up lists for the target addresses, then again in the multipop engine, specify the list names as the forwarding addresses. Again, I have not actually tried this but the idea behind it should be sound.
Good luck !
Kelvin