Allow group leader to set a specified world as a hub. If a group member sets this as their homeworld, it will automatically open the instance to the Group. Once everyone leaves it will close the instance waiting for a new member to login or return to homeworld. Opening the instance shouldn't be a problem as you can already set your home world settings to invite, friends, or public.

Show as "Group Hub" in Group Instances tab and if someone sets this as their homeworld have VRC scan for the open instance, if one does not exist, create a new one.

Alternative Option

When selecting "Go Home" change options to "Personal" "Group" "Default" and change the "No" to an X on the top right.