I'm not in the same state as Tesla, but the rules are the same. Kids have no say until well into the teen years. Not having the kids available for pick up by the other parent at the times specified by your agreement would be contempt of court. My kids hate transitions (almost by definition really), so there's a lot of fuss when it's time for them to go to XH. I tell them the schedule ahead of time, and we go over who will get them from school and the next time they will see their father every morning
I never give them the impression that they have a choice. It sounds terrible and mean, but they get used to the schedule like any of their other obligations. I look at it the same way as not keeping my 8 year old home from school just because he doesn't want to go. It is a huge adjustment and both you and your ex (if that's even possible) need to be sensitive to the kids' feelings during the transition. For example, your exh should not react angrily if your dd doesn't want to stay. The kids do need time with both parents, and a steady routine as they adjust to the new pattern. Good luck, it is a tough stage for all of us with young kids.