I don't know what your ex is like but this is exactly what mine says and she's lying!
"I'm not just going to make decisions for them without them feeling comfortable and happy with arrangements. I will always talk to them first before I put and proposal for change forward."
Because she thinks it can convince me (or someone else) on paper and because she is asserting being the important parent. Mine has said things like this when I know full well my son doesn't agree with her. But he soon felt her wrath when he told her that actually he did want to spend more holiday time with me. The kids have no option but to agree (or could be persuaded with treats!).
The last line - she is aware that the eldest ones "wishes and feelings" will be taken seriously by a court and those wishes and feelings will be what her Mother has said.
It's the way she talks about "home" as well, as if her home is "home" and yours isn't. Mine does that too. It's very much saying - I am the resident parent, this is their home.
"They said to me it's getting too stressful on a Monday morning getting everything ready to come home and get ready for school."
How is it stressful to go straight to school on Monday morning from your house if they come straight from school on Friday in their uniform with their school stuff? Why would they need to "go home" on Monday morning before going to school? Do you live too far from school to take them to school?
Yes the CMS and school shoes request probably does have something to do with it.
So no mention of changing a night then? Just chopping that Tuesday night?
You're not going to change her attitude that her house is "home" and their main residence. Best thing you can do is get as much time as possible. I had many correspondences back and forth before court with my ex talking about son's "wishes" and me talking about his "best interests". After all kids can't always have what they want and what they want isn't always good for them.
So you could try one further response:
"Dear Ex Name
Thank you for your message. I think, as adults, we can easily organise practical matters so it isn't stressful to go straight to school from their home with me on a Monday morning. However, I would be happy to agree to their week-ends ending at 6pm as before, on the basis that there is some flexibility over this if I ever need to return them later (for example if going away for a week-end) and that occasionally they could stay over on the Sunday night. I think if they come straight to me from school in uniform with their school bags, there is no real difficulty in having everything they need to go straight to school on Monday morning, whichever parent they are with.
As adults and parents, we are responsible for ensuring the childrens relationship needs, as well as practical needs, are met, and I think the best way for both of these to be met is a regular, stable schedule of significant time with both parents.
If you wish to reduce week 1 to wednesday and thursday only, and are not in agreeement with the children staying on Sunday nights on a regular basis, I propose that instead the children spend Wednesday and Thursday night with me each week, and every other week-end until 6pm Sunday. This would mean their time with me is the same as before, rather than being reduced and hopefully will be agreeable to all. As such this would be
Week 1 Wednesday and Thursday nights with me
Week 2 Wednesday night through to Sunday 6pm with me
Please let me know if this is agreed"
I would try sending that. And see what the response is. The important thing is that you are seeking her agreement to things. She of course is avoiding any discussion of agreement and making out it's not her, it's the children, but she has parental responsibility and is expected to reach agreements with you as a co parent. So an email like this can be good evidence later, of how difficult it is to co parent and reach agreements and how she uses the children to send messages.
. Wait to see if your ex gets back to you about this Thursday night first.