Our 8yo DD is going into third grade. In first grade she had a friend she spent a lot of time with, in second grade this girl ignored her and wanted to play with another group that had an incredibly mean kid as the ‘leader’ and would scream at my DD to ‘go away’. DD is nervous about going back this week as they’re all in the same class again, I don’t know how to tell her to prepare. WWYD?

You should talk to that mom who's worried about protecting her first-graders' friendships. Definitely not a sure thing even in person!
I think the UB consensus was, 1) encourage your DD to make new friends outside of school, enrolling her in ballet/sports/other extracurriculars accordingly; 2) see if she can be placed in a different section from the mean girl"leader" at school; 3) ask the teachers involved discreetly to keep an eye on the situation; 4) have her throw a fun outside-school event and plan in advance with nice moms to have a pool of their girls attend and exclude the "mean girl"; 5) talk to the mom of the "mean girl" and try to negotiate a friendship/detente; and 6) if none of the above works, you have to switch schools after a year or so (this year I suppose you could go remote?), making sure the mean girl situation at the new school is more manageable, bc they are everywhere.
Thanks so much. This is very helpful. I’ve noticed that the mean girls mother is also a complete witch so I think it will be better if we avoid them altogether