C.A.
They do make something that you put on their nails that tastes really nasty. Believe me I used to bite my nails and I ended up pulling the skin off the side and it became infected. I had to go to the Dr to have it lanced and I never bit my nails again. Ask the pharmacy if they still make it and use it everyday. The pharmacist my recommend something to you also. I am not sure what it is called but they pharmacy may be able to help you.