Using military strategy example, how big is the battle and what outcome do you want?

I have bought many houses where the pet smell was basically impossible to be removed without removing the drywall.

Purchase price: $151,000 Cash invested: $44,000 The house smelled like cat piss, rising damp, had unleveled flooring, everything outdated & more.

There are thousands of cases where the same property is sold to multiple people, and you get stuck in legal battles for a long time.

Now if they aren't cleaning the cage and the room smells I'd tell them they have to go. 

Evict if you find or smell anything inside the house.

Just on quick glance, you can see that 1-3 bedrooms are very overcooked and you'll have an uphill battle getting occupancy.

You're fighting an uphill battle to eitherget money, when it's not scarceor help someone, that doesn't want your help.My parents won't invest either, my friends all said no when I started too.

The smell is really awful!

This is never a good situation.. what you can do is to work with her and tell her that she is equally laible and has singed a legal document that can be held in court of law... she should just pay her part of the lease value to get out... i would consider giving her some relaxation on payment to motivate her to pay, rather than going into a legal battle... then you can renegotiate with the other tenant if he is still staying there... eviction of course is the last resort and yiu can do it since one of the tenants have brwached the lease, which legally puts both ofvthem at breach, but eviction process is rarely landlord friendly and some tenants know this already...