Baby Registry Stress

I posted something before about people not wanting to purchase from our registry. Well my MIL has recently been trying to buy things from it, which I appreciate. However, with the clothes, she hasn’t been paying attention to the sizes I chose and is getting whatever size she wants. I don’t know how she’s doing it or why she doesn’t ask if she’s not sure what size we want. But it irritates me because I chose the sizes based on the age/season it will be worn. So getting a different size could mean he won’t get to wear it because I’m not taking him out in summer clothes if the weather is cool. I don’t want to sound mean or anything because I’m glad she’s ordering from the registry, I just think she should avoid ordering the clothes and maybe get other things since for some reason she won’t get the sizes that I’ve indicated. But of course I can’t tell her that, so I guess if he can’t wear the stuff she gets oh well? Lol