I agree, it is like me with grandparents: MIL and FIL use to give a lot of junk to F (and luckily he doesn't really eat it actually because he is happy to eat a candy or two, and he's done with sweets, and he really doesn't love chocolate). But really, what can I say? If they give him candies and treats every two weeks when they have him, I don't feel to complain too much, I think that the bonding time that they spend together is more important... and I still remember when my grannie bought me chocolate that my mum wouldn't have bought me, it was one of the magic things of staying with my grannie, so I understand this so well! Differently would be if F was eating sweets or chips every single day at home and refuse other food.