Its a simple fact any decent alliance player cant and wont put any effort defending the group he sits in. As you will need to support the alliance with the incoming and to make it an effective force, support with the attacking aswell. I myself cant see any room to help your group in that case.
Private planet is only reasonable thing to support your group for real and have the reason to. Weather we allow some randoms in them is a case if we want to believe the randoms lack an alliance, otherwise its just a free gal status
