Taking player subgroups onto separate maps?

Hi folks - So sometimes a subgroups of characters enters the cave while the rest remain outside.  I would like to be able to move a subgroup of characters onto a new map while the remaining characters stay on the old map.   Ideally, voice chat (but not text chat) would be tied to each map, so that the cave-exploring characters could talk with one another (and with the GM) while the outside characters could talk with one another, but the two groups could not communicate with each other.  It might be necessary to freeze player-initiated token movements on the GM-unattended map, too, especially if dynamic lighting is set.   I, as GM, would have control of this, and could myself choose to speak to one group, or the other, or both at once  (in the latter case the two character groups could also talk, I guess).   If the game had two GMs, one GM could run each part of the game  (haven't tried two GMs yet, if that even works in Roll20).  WIth one GM, the 'outside' part of the party could talk with one another and ping the GM by text chat if they decided to race into the cave spontaneously.   Thanks for listening. Thom

Third party voice chat allows for rooms (Ventrillo) till roll20 implements. Could start a second campaign for the 'in the cave' group, tho clunky. Make a large enough grid to support two maps, one map inside, one map outside, dynamic lighting to control LOS. Third Party chat and you can do all you wish with existing tech.

I have used what Voth said (minus lighting of course as I don't have that feature, players were merely forced to remember they aren't allowed to mix character and player knowledge)

Couldn't you use two maps and require players to use 'whisper' mode text chat? If they are shouting loud enough to be heard by  anyone they can use normal text chat or video/audio. Splitting audio/video sessions by map and then poss merging them later would be nice but is perhaps IMHO  excessive. Of course if both groups re large 'whispers' could be a pain but probably more realistic. Try communicating to 6 or 7 people at the same time across a distance while remaining undetected. Unless the game is modern or SF and everybody has comms.

@Voth, you're good with the existing-tech workarounds.  Might do that.  The "second campaign" is probably cleanest  (we finally got decent voice/video chat with the Google+ framework in Roll20 and I don't relish revisiting the land of unreliable chatware).   @LochaberAxe - that would work, though personally I really value the voice/video chat for communications.   All that said, I still think subgrouping/multiple active maps is a good idea for the Roll20 stack.