Hey thanks for the advice! I also considered putting collars on them for this kind of bowl that only gives access to the cat with the right collar on which sounds neat but I'm not sure if it's so effective at keeping him quiet (wife works at home).

Regarding the teeth, I'm not against their removal so to speak, but the anaesthesia at his age is a risk many vets aren't willing to take especially at his weight.

I don't want bad teeth to cause kidney diseases but at the same time I don't want him to die trying to reduce the risk of that. It's tricky...