I don't see the issue - why do you have to exclude indies at all? What's this need for elitism in defending PoBs when you could just win by numbers and get more PvP action to everyone? There are now multiple repair ship freelancers for one you could have just paid. If the attackers hire them instead because you made the group public, so what? you are generating player activity,can pay them more etc.
And I assume all metagaming siegers know there is a discord group that has a bot that pings every time a PoB is under attack
Let indies in, advertise it openly on the forums and in external servers, and have a locked hashtag for only people you trust but ping the open one every time there's a siege and bot pings attack message. This will be good for everybody
