I don’t think posting about the outing is unkind it's just what kids do these days.
These girls likely won’t think twice about sharing everything on social media, which is a bit of a problem in itself.
It’s not just about the person who sees the photos and feels left out, constantly updating their lives minute by minute can make them vulnerable. They chase ‘likes’ and validation, which impacts their self-esteem.
If your daughter is feeling strong enough, she could have a little fun with it though. She might want to 'like' or 'heart' a one or 2 of the shared pictures and (definitely not the 'queen bee''s ones though, if there is one).
Then make sure to plan something fun for her today whether it’s taking her out yourself or arranging for her to meet up with a friend from outside the group, or maybe a cousin.. Have a great time, and she can share her own pictures to show she’s having a great time.
The key is for her to act like not being invited doesn’t faze her at all. She can keep it cool, confident, and totally unbothered showing that she’s doing just fine, with or without the invite.
At school, she should start seeking out some other girls to spend time with but be super nice to this group, just more detached and a bit above it all.