Thank you for sharing
I think simple testimonials like this will help many people. Sorry for the skin probs Grandpa had, but I'm happy that it's finally solved.
LOVE your family
sounds great, to have all that variety in a fam! I wouldn't worry too much about the weight gain. When dogs switch foods, they may gain or lose weight, depending on the nutrients they're getting. If it's within the normal lines, it should be ok. If you're very worried, the vet will confirm whether the weight gain is good or not.