WWYD 13 yr olds' friendships

[GoingBackToBed]

More a wwyd, sorry it's long.
There are six 13 year old girls in a loose friendship group that have been meeting a few times over the holidays.
2 of them are mine. They go to different schools.
In particular there is one girl who seems to manipulate the group and cause a lot of drama.
She 'won't let' 4 of them meet up without her. They did once and even now, weeks later, she claims that this was bullying behaviour as she felt left out.
I offered to take the 4 who seem to get on best, shopping and in the end we had to re- jig the day so that this friend could also come (my 2 find that the dynamics are very different if this girl comes along and from a practical point of view I couldn't fit more than 4 in the car).
They've arranged to meet up tomorrow, originally just 4 of them. Then my dd's suggested asking one of the other girls as well. At this point the manipulative girl started a drama about how she didn't want to invite this girl, even going as far as suggesting that everyone should have a chance to feel left out, so on each subsequent trip, one girl should not be invited.
I am really clueless in knowing how to help my dd's deal with this. Ideally I want to let them sort it out themselves, but they don't know how to, and neither do I.
On the one hand, no one should be deliberately left out, but you can't always invite everyone to everything.
Any ideas as to how to handle this situation? Thank you.

So as not to drip feed, (I feel bad saying this, but it does illustrate what this girl is like), she will check my girls' phones and if her picture isn't on the lock screen or wallpaper, and they have a different friend's photo, she will accuse them of bullying her.
I want to teach my dd's to be compassionate and kind, but at the same time I want them to have boundaries and not be walked over by a manipulator.

All I can think to suggest is that they work on making a different set of friends, but this seems unfair as they like the others in the group, and indeed they don't dislike this girl, they just find her behaviour trying.

I can only offer that at their age girls can be incredibly fickle and/or fiercely loyal.
My DD (a bit older at 15) has a group of friends that go everywhere together. Obviously though there are times when one is busy etc. Sometimes if they've arranged a trip to cinema/shopping etc and one can't go then they all won't go (to be loyal!). I tell my DD this is silly cos why should they all miss out?! Apparently, I don't understand
Your DD 's friend sounds like hard work and a bit immature although they're still young and I don't think they form established friendship til a bit older. I know it's hard not to get involved but sometimes you just have to let them find their way. My DD didn't have these friends til year 9. Year 7 & 8 she tried maintaining her primary school friendships but they just grew apart. x

Thank you for taking the time to reply. I'd love to stay out if it, but i get drawn in by the bonkersness of the tricky friend. Anyway, they seem to have sorted something for tomorrow, so i guess all i can do is listen, empathise and try to not get involved.

I would listen and offer advice but ultimately stay out of it. Today's enemy is tomorrow's friend amongst many groups at that age. They'll sort it out one way or another x

Can your girls split and take one friend out each?

Or each invite one friend over, so less of a group activity?

Do they tell this girl it’s not up to her who they invite?

The each inviting one friend each was how the 4 caused the original upset. They naturally split off in these pairs so it made sense to invite the original 2. I'm quite happy to have more, but it does change the dynamics and sometimes they just want to hang out without the drama.
The added problem is that in school one of the friends is closer to the tricky friend, so i think she feels stuck between a rock and a hard place when these issues arise.
Hey ho, just glad I'm not 13 again. Although i never had these issues, so i feel unequipped to advise.