You are definitely not being unreasonable and it must be really hard when she badgers you like this.

DS likes to take things to childcare (he is 3.5) but I really try not to let him and explain that it isn't fair on the other kids cause they might want to play but he won't let them, I tell him that it isn't fair on the teachers cause they have to keep an eye on it and that it isn't fair on him because how would he feel if it was broken or lost. I am lucky that he seems to be mostly accepting of that. As a last resort I can be pretty harsh with DS and threaten to throw his toys away if he doesn't stop going on about it and that seems to get him to stop.

I think if we were having bigger issues that Tanster has some great suggestions so that might work.

Goodluck navigating and negotiating