Why should the events be in a group?
What part of creating the events and actions written down by lennaert do you not get?
When the host leaves the room everyone gets kicked out..
Lennaerts events make it so both the peer group and the host group (why those should be present is explained in the multiplayer tutorials) are deactivated, the players reconnect to the room automatically and for one of them the host group is activated, for the others the peer group..
This is offcourse kind of a "hack" and because of that some things might not automatically work..