Obviously it depends on your DS. I would want to resist getting into the ideology behind this if you can, because 7 is very young. But I agree that if you do have to get into it then best to go with ‘some people believe’ like you might with any religious belief.
But actually, unless you feel you need to go there does anyone really have to get into the topic of ‘Sally is now a man’? Seeing as you can’t really change sex after all. Most importantly: Seeing as kids aren’t there to validate adults, of course.
So apart from changing a name which you can say truthfully to your kids, is a fairly run-of-the-mill thing to do, can’t it just be Steve’s own business how Steve wants to think of their own gender?
If you’re GC your kids are likely to already think that the people they know who are unnecessarily into believing ‘that’s just for boys!’ or ‘that’s only for girls!’ are being a bit silly. Because that stuff will be coming up in their discussions around games, toys, clothes etc and you’ll be talking about that.
So I think it’s too much that the head coach is expecting kids to change to new pronouns or that Steve would expect this. (We don’t know if it’s come from Steve or the Head Coach of course)
Why does what pronouns your DS (aged 7) calls their teacher, honestly matter to a grown adult? Given this will normally always be out of the teacher’s hearing anyway.
So I would be saying to the Head Coach that your kids will absolutely be respectful around the name change, and they will continue to treat all their teachers with the same courtesy they always do, but you’d expect that an adult on the staff would not expect of the children, that they should use any terms which would confuse them.
Then you could say to your DS, Sally has changed their name away from Sally because they didn’t like it that much.
Now they would like to be called Steve. That’s fine and we’ll all be using the new name Steve, adults can decide to change their names for all kinds of reasons.
If asked why Sally changed name, you can say it seems like Steve is more into things that they think men or boys like, (even though anyone can like anything!) and so maybe they didn’t like being called Sally because it wasn’t a man or boys name.
Your child will probably say, but Steve IS a girl or woman still, and you can just say yes but Steve is the name they want to be called now so we’ll be doing that. Nothing wrong with changing your name etc and it’s not really our business why Steve prefers their new name. And now, have you got your kit ready for the next lesson, and what shall we have for tea tonight?