Need help in stopping beard chewing

[Pottydottie]

Please could someone help me in stopping Molly's fur being slowly chewed away.
Molly has so far got a blad patch on her front leg, part of her beard chewed short and an eyebrow.
Have caught Poppy the Cesky doing the damage she using her front teeth nibbling on molly's beard and molly just layes there letting her do it.
I have stopped her chewing Molly's fur when i'm around but she now does it when i'm out.
Is there nything I can put on her fur that will turn Poppy off chewing it?

[snazy]

You could try bitter apple spray, I'm told most dogs hate the taste of it. Obviously just be careful spraying it around her eyes