You are very sweet to invest so much time and concern into this issue.

Here is my free advice: It does not matter why they got a dog, whether the child has any particular diagnosis, etc. You are the landlord, she is the tenant. Your relationship is clearly defined by law. Please, make your life a lot less complicated and divest yourself of all concerns about all the other stuff. This woman is trying to play you for a softie. Don't go there.

Make extra sure your records are in perfect order with her. Document EVERYTHING. Dot every "i," cross every "t." When she defaults on her rent, evict her and go on with your life.

Bless you for trying so hard to be welcoming and accomodating. Please, don't get enmeshed. You deserve far more peace in your life :-).