Four month old being over fed by exes mum

Me and my partner split months ago and Fridays she goes to there’s. She is always so unsettled when she goes and I always get phone calls that she’s screaming and won’t settle. My little girl has extreme reflux, and cows milk allergy isn’t gaining weight due to not wanting to up her feeds so I have been advised to add some purées to her diet. I have been very specific with them what to feed her and how much. Today I forgot to pack her food and they went and bought her one. For some reason they then went on to feed her a whole portion of puree (100ml) and apparently she enjoyed it. (I am absolutely furious, who thinks it is ok to overfeed a baby so much and I wouldn’t mind she’s so small for her age. She’s been screaming from 3pm at there home and returned very unsettled with obvious signs of tummy ache. I know introducing foods isn’t something everyone agrees with but every baby is different. I just want to know how I bring this up to them? I’m trying to not be a controlling mum but are they serious? 🤬