There is this stuff called bitter apple spray your friend may want to try. It supposedly works very well, but when we tried it on Bandit during his puppy chewing phase he just licked it off the couch (which was what he chewed
) lol. Nala's chewing phase was all about my flip flops but we would just clap them together to make a loud noise and eventually she stopped. However, they were both younger than 9 months when going through their chewing phase. I'd give the bitter apple spray a try, or you could try crating her or using an ex-pen when nobody is watching her.