I was your DD in the exact same situation at her age and from a baby of a few months old. My parents were extremely hostile to each other so you are born doing well to keep that part of it cordial.
However I will also die on the hill along with PP above, that 50/50 is very unhealthy and shouldn’t be allowed for kids but especially for young kids. It’s absolutely no credit to your ex at all that he has insisted on this shitty, adult-focused arrangement.
Especially when the separated parents don’t live extremely close by to each other or don’t have very good relationships with each other, which frankly that’s a very tall order, then 50/50 is a recipe for trouble. People don’t split up for no reason when they have very young kids. I do get it.
So given this is distressing for your daughter, could you both massively bite the bullet together and do the thing where the parents transition out of one main home week on week of, so the child can stay put? That’s the only way I think it could work.
Posters saying ‘just pick them up from school’ have no idea of the knot of anxiety that that kid will be having all day at school, about who will be picking them up and what if they’ve forgotten to pack something, or there’s a playdate their parents don’t know about. Or they’ve not got their PE kit for two days time or their toothbrush, or the book that they need to bring in on a Tuesday, or whatever it is. Believe me, it’s horrible. Let alone if there’s a party or a play date, and the other parent wants it to be ‘their’ time with the child instead because they’re rigid about the 50/50 spilt, so the child misses out on a lot of the fun things.
Also when you pick up your children under 50/50 from school there is obviously the total lack of handover between parents about what’s going on for the child. It can be very hard for the child to tell the other parent about what’s going on. So you’re causing the child just to have to deal with a lot of stressful stuff alone which becomes a habit, as does the people pleasing that the child has to do.
This is because the child has to slot in neatly with whatever is happening at the other parent’s house and whoever is there and whatever is going on. I think 50/50 is awful, honestly. The number of adults who will say they wouldn’t live in two places shows you that. You never feel settled.
I’m really sorry because I can see 50/50 wasn’t your plan and I know this can’t be nice to read. You sound like a nice thoughtful mum so please try and make this change if you possibly can. My earliest memories are all of distressing pick ups and drop offs between my parents. It’s really upsetting to do this on purpose to young children. Sorry to be so blunt.
If your ex won’t get on board with the fact this is not working for your daughter, and as it’s court ordered then I don’t know how it works but please go back to the court and say it’s not working for your child with as much evidence as you can manage to get from school or anyone else.