This is a quote directly from the programming book:
Allows the assignments of stations into call pickup groups. There are 99 pickup groups in the system. An unlimited number can belong in each group. Stations can only be in one given group at any given time.

I have never tried having a station in more than one group but I think it will give you an error if you try to pick up from a group you aren't in. One way around this may be that you can use a virtual station and assign a different station to each pickup group then give a DS button for that station. Once it starts ringing then they should be able to press the DS button and answer that call. Of course you can still label it group #... but they will not know the difference. Since the latest software allows you to answer calls using a DS button.

My other question is, do you have everything working as it is supposed to be? Do you need help with anything else?