I know. I guess I just never expected it to be this difficult. Not that I expected STBX to say "yeah, take the girls" but I thought we'd be able to come to a fair arrangement that would work for all of us. But seriously, the negative criticism is just as helpful as the good.
I'm sorry and I'm pretty sure you don't want to hear this, but have you considered having the girls stay in the same house and you adults moving back and forth? If you really want to give the girls consistency and stability, this to me sounds like the way to go - otherwise, you're creating chaos in their lives due to your decisions. I know families who do this (houseshare) and it really is the best environment for the kids, ultimately.
That said, I'm sorry you're going through this. Sounds like a pain and a half, and I hope it gets worked out and fast. For everyone's sake.
Maybe explain to DD that she is going to start at X school and she may have to switch at some point. It's kindergarten. She will be fine.
I wouldn't do this. I just had to switch my ds after kindergarten and I told him in the spring as soon as I found out the school he wanted to stay at was full and we couldn't get a permit to stay. It caused him (and me) a lot of anxiety that really wasn't necessary.
My honest answer, you need to find a place near your marital home. I know that's not what you want to hear, but if you are really trying to make this transition smooth for your kids, having a new house in a new neighborhood isn't the way to do it (unless of course that is the ONLY way for you to get a job which doesn't sound like the case here). I know my ex would have loved to move to some hipster urban LA neighborhood, but stayed in the little beach suburb we lived in together because it was best for ds.