Yep, that's one of my biggest bug-bears about CCM. Why can't a line be member of multiple pickup groups?
We have secretaries who have to pickup over 9 team's worth of phones. However, since those teams are in individual pickups, the secretaries would have to memorise all 9 group ext numbers.
As I previously mentioned, since we forward to voicemail after three rings, group pickup is useless. But multiple pickup groups would allow the secretaries to pickup a ringing phone fairly quickly, without having to wonder who's team is ringing. (Made worse by the fact two of the teams around around a corner - they can hear a ringing phone, but don't know which team's phone is ringing, rendering group pickup even more useless).
Please post back if you find a solution to this one!