~7 years ago, I gave my fiancee a cat for her 17th birthday. my fiancee's mother agreed to take care of the cat when we went off to college. 2 years after I got my fiancee the cat, we went off to college and my fiancee had begun living with her father (Her parents got divorced). Since then, the relationship between my fiancee and her mother has become volatile and the mother is refusing to return the cat to my fiancee and I. In the meantime, my fiancee would stop over and spend some time with the cat but it was very difficult because of the hostile environment in the household.
The cat is still getting vaccinations under my fiancee's name and she fulfills part of the legal definition of owner of the cat in the state of IL. The problem is, the mother has been financially taking care of the cat in the meantime. Do we have any recourse for getting the cat back?