Dad with dementia eats most of the food, snacking constantly, leaving little for Mom. Advice?

Yes, Mom with worsening pain of arthritis. insists she can take care of Dad in their home. Dad is incontinent at night and needs supervision to take his meds twice a day, do his PT exercises and do something besides eat. Kids go there 3-4 days per week to do laundry, shop, cook and freeze some meals, help with finances but it is not enough. We just had discussion that we must talk with our Mom about getting a home health aide to get Dad up, clean up his bed, do lauindry, supervise meds and exercises, do some basic housekeeping at least 5 days a week. As for the food, Mom gets his breakfast cereal and makes or microwaves dinner, but he wants to snack all day long, anything he can just grab and eat. He sneaks it now, going into the frig and cupboards when no one is in the kitchen. He'll keep eating until all fo those typds of food are gone, no matter if we buy more quantities and even freeze otherwise hide some behind things in frig or go shopping more often. Mom puts out a few fruits several times a day and keeps the rest in her bedroom. Also puts keeps a few packs of crackers or slices of pie/cadk etc. in kitchen at a time. She needs needs to have convenient foods like yogurt, sandwich fixings etc. for herself too.

I don't get it. Wouldn't you just buy more food? Or shop more often? If dad's eating all the yogurt, buy twice as much. Keep some Ensure in the fridge. One of their variants has 350 calories. That's a decent breakfast or lunch.

I must be missing something. My solution seems so obvious. Buy more food.

If mom can't even assert herself enough to stop him from eating everything in the house I wonder what is going on other areas of their life. What happens when she tries to stop him from eating, is he angry, or even violent? Why can't she simply remind him he has already eaten or re direct him to a different activity? Or is he raiding the frig in the middle of the night so she can't get any rest?
I agree that it is perhaps time to reevaluate their living arrangements.
Another thought is that he could go the adult day care to give her a break and occupy him with something other than eating.

It's clearly time to change dad's living situation. Is mom attempting to be his caregiver? If not, who is? More information would be helpful.