You can definitely feed them comfry but I'm afraid you won't have a comfry patch as such if they get to it regulalrly. You could cordon off because comfry will crop several times a year. Let 'em at it, then cordon off again, They'll love it.
Aslo put some asside yourself in a large, resealable jar, topping up with fresh leaves every so often. No water required. Leave for a year at least. It will rot down slowly and leave a brown liquid. After a few months more this will go black and essentially smells not bad but don't go down the pub waering this as aftershave. The Romans used it for rubbing on sprains a breaks. It was known as Knitbone. Excellent remedy for your sportsmen or old farts with dodgy pins.
Agreeing with another poster it smells like death when composting down in water. BUT it is unbeatable as a fertilizer. Use about a largish cap full to a gallon of water. Keep it tightly sealed in a closed barrel. My neighbours actually called in Dino Rod because they though they had a sewer burst. They check 8 houses down the street. I couldn't confess.