As much as you enjoy the breaks, I'd threaten to stop the visits. My sister's done the same thing with our Mum, and Mum stopped doing it straight away! Just say, 'Listen, I've asked nicely quite a few times, but if I can't trust you to respect my parenting wishes when you have my son, I won't be leaving him in your care'.

I know, easy to say from my end Hope it turns out okay darl