I am not certain that a "good weight" necessarily means a "healthy dog" so I feed my furry babies based on ingredients, trying to feed them 'clean' and 'natural' nutrition, and I am not very appreciative of having unwanted items fed to them without my permission. I am fortunate that my furry kids do not like most things that 'strangers' try to give them.
I can very much sympathize with you...and since it's your MIL, it is even worse, perhaps. I hope you can come to terms with her and at least get her to respect
your wishes for
your dogs.
Since it is very difficult to get 'clean' food for humans or pets, perhaps you want to give your MIL the link to the pet food database so she can check out what she is feeding her precious pet...the ingredients/chemicals are the same in people food, although not everything put in dog food shows up in people food...but it
might be a place to start her thinking about what that baby is eating. Here is the link from my thread:
DOG FOOD INGREDIENTS: THE FIRST SEARCHABLE LIST!
For sure, try not to become overly emotionally involved in trying to 'change' her views/ways of feeding. I think it will mostly stress you more, and for what reason should
you be further stressed? The 'facts' as told by an 'objective source' often speak a language to those close to us that we cannot...LOL
Good luck!