Daughter wants to move in with her mom

My niece got custody of the kids. When one got older she didn't like staying with her mom anymore and wanted to stay with the dad, same reasons your daughter wants to move, that parent lets them get away with everyone. Well, turns out the grass isn't only greener on the other side. She came back, couple years later another daughter wanted to do the same thing. Live with dad, the previous one said it's a bad idea, then talked about the crap that happened. She didn't listen, found out it was worse than what was said. My niece, what did she do? She supported, emotionally, both of them, but said you can't be playing one parent against the other, and can't just come back in a couple of months. Now both kids are back with mom and realized it wasn't a good idea to be with dad. Will this work for you? Every situation is different, that's for you to decide whats best for your daughter. But it's a decision not to be made lightly.