Just as we don't get along with all adults or want them doing what we are doing so do kids. That does not mean they can be rude or exclude. If she doesn't want to play with both girls then she can play by herself. This encourages the other two girls to play together. If they can form a bond then it will be easier for your daughter to want to join in too.

Take a look at what they are playing when they choose alone activities and watch how they use toys they all use to see if they are at the same play skill level ie level of imaginative play, topics of interest and then intervene to mediate as necessary to try and get them on the same page. You may have to play with them to start and then gradually back away.

Is the new girl from their school as in they have a history already or is this a new person entirely?

Not sure I would be making her sit out and not play but redirecting her away from what the other girls are doing to find something to do by herself. As in it is ok to not want to play and yes they can be downright rude at this age and while that is not acceptable they don't have a lot of ways of getting their point across. Even if you have to set up stations for alone play and some shared play and then you can have rules for playing in the together places and if abused the child must go to an alone station. Just watch that one of them is not getting so upset they just play alone and don't even try a together activity.