My son is allergic to peanuts but...

Boyfriends family (who we live with) keep buying peanut-related products. They have kids and they buy the snacks for them because they don’t want them to be “deprived”. Just recently they bought peanut butter cookies,peanut butter, peanut M&M’s, and ritz peanut butter crackers. I honestly wouldn’t mind, but they let their kids (2&3) walk around with these snacks so I’m afraid my son will come into contact with them (he’s 18 months). I don’t know what to do. I can’t afford to move right now so we’re stuck here. We do live in the basement portion of the house, but we do go upstairs a lot because there’s no kitchen down here. It makes me angry that they don’t take my sons allergy seriously.