questions about groups and multiplayer

[tacticalnuggets 24]

So if I make a group completely playable in multiplayer, once somebody has joined that group I can always have a variable point to that group, right? I've found that in ArmA2 when someone dies they are still apart of that group, and when everyone dies, the group is still there and everyone is apart of it. But what I'm trying to figure out is if a guy joins a group then quits will the variable pointing to that group be the same, or will the group be deleted? And if a person joins again in the same group slots (in the lobby) will he be in the same group? I need to know this because I'm going to be using groups to store variables in multiplayer and provide group dependent features. Its poorly documented currently.