Yah, that's one of the reason why we don't use the dog litter anymore. I put newspaper in the litterbox and it work out great with our baby. She is almost 7 months old now and litter box trained.
It's hard to get a Yorkie not to eat or chew on dog litter. Once their mind's make up, you got a problem. Even though I know it should be safe to eat the litters since they are paper based, I don't want mine to mess with litters - that's the toilet after all. Sorry, I don't really have the answer for you.
But paper in the litter box works out great for us. When we are visiting friends, we would just put down some paper for her and she would go on the paper when she had to go.
Maybe someone else here can help you with this issue. Good luck!