Ye, unfortunately I can only make it invite only or by admin approval, there's no public option. That's probably for the better, anyway.
Um, ok, some more bad news, apparently we're soon to reach our limit for members, and now if we want more members, we have to turn off 'group chat'... which is like, the only reason to use this
We can take up 2 more members, then we will disable new members from applying until microsoft ups their limit.
Everyone should write to microsoft and tell them to allow more members into group chat.
You can send your feedback here:
https://feedback.live.com/default.aspx?mkt=en-us&productkey=WLGroups
You can send this message if you like:
Quote: "
Hello. You guys should up the limit for the maximum members before group chat is turned off.
We're well aware that a chatroom with more than 20 dudes is hectic. We *want* that. If members don't like it, they can leave.
So please make the member limit unlimited!
Without this feature, we find Live Groups to be pretty useless

"
"I acctually quite like this site. And noone will know because this is a secret..." - Anonymous
Shhdb.com