I have 2 bichons (both females, almost 6 yrs old) one is 21lbs and the other is about 16 lbs. The 21lb one, coco, actually lost weight, probably due from not eating. We switched food a little to see if she didn't like the previous food and that didn't work. We don't know why she hasn't been eating (usually she's the one w/ the appetite) My mom, today, gave them both chicken and white rice as a meal. Of course this is OK I guess, but I don't want it to be a habit, they need to not be dependent on people food. What can we do?

This is a common problem, or at least different ones with different solutions. I put most of what I know at ''My dog won't eat.'', https://www.askmehelpdesk.com/dogs/information-articles-our-dogs-expert-labman-53153.html#post254171

Please read it and then post back if you want to.