You are not being honest in this post! You can delete your questions, but until they pull it, your answers are still there. I've answered some of your previous questions. Your divorce is not amicable. You mention his girlfriend b/c you have issue with her. What you are trying to do is out of spite. I am sure he will fight you on this and your children are old enough to be asked their opinion.
I get it, you're hurt. He did you dirty. You are going to have to let it go. You can't control him and you are hurting yourself and children in trying to.
You can get your life together where you are or you can leave and be the one to fly in or fly them out to you. You have to stop, if we can see through you, what makes you think his attorney, mediator or judge wouldn't?
My original response:
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I think there are a lot of variables here that weren't given. The bottom line is that the courts look at what's in the best interest of the children.
You move back home and you don't even have a job, so I assume your sole source of income would be child support? Then you want to reduce that by 20%, how are you going to survive? How is that better for them than being in your current state? You want to go to school, that's good and all, but how are you going to support them while you are in school? Who will watch after them? These are all questions that are need solid, reasonable answers.
How often does he see them now? Every other month for a long weekend isn't much. That's only 6 times a year they will see their father and that's only if he can afford to fly them out. Really if he agrees to this, you should be the one flying them out, not him. How is that in the best interest of the children?
If, during the past 5 years you haven't been able to get home to visit family, why do you think it's going to be easy now? You are also talking about taking your girls from everything that they know, so you can start over. That's not really balanced.
I don't know how old your children are, but if they are a little older in age, courts sometimes ask them what they want. You didn't tell their ages, so I don't know if that's the case here. You have an easy relationship with him right now, but try to take his kids away from him and it can go left fast.
Not sure what his girlfriend has to do with anything, unless your thinking is that he has already started to move on and you want to do the same.
You need to think long and hard about this then discuss it with your attorney. When you are thinking about it, consider his relationship with his daughters now. If he is very active in their lives, gets them on a regular basis, pays his child support on time without issues, my guess is that he won't consent.
It's hard being away from family, but you have to remember that he is their family.
Good luck.
ETA: If he does agree to this it needs to be more like he gets them every summer for the entire summer and long school breaks. That is the only way it could be semi- balanced. So Spring break, Christmas break and the day or so after school ends until a few days before it starts. Keep in mind the toll it will take on the girls too.