Thanks for your reply, but I'm sure that you have not read my post or I'm a bad informer.
If You have a version of Dolphin 6.0. where you in Admin=>Settings=>Membership Levels=>Manage Membership Types/Membership Actions can control membership actions(what are allowed or not allowed) regarding "Groups" and "Events", then please advice, otherwise I advice you to read all sentences carefully before you leave a meaningful reply.