Anyone have success regulating mental illness meds when those they're caring for refuse?

Brand new to the forum, excited to have found it. My MIL is moving in with us in two weeks. We are moving her from NC to TX. She is independent, but refuses to take her meds for bi-polar and paranoia. She refuses to see a psychiatrist, but we're going to work on it. We've heard there is a once a month shot to support her illness, which would be amazing and likely solve our issue. Until then we are trying to find a way to get her regulated. She may live with us forever, or she may get an apartment, etc. if we can get her regulated. Day by day for now. Appreciate any advice you all may have. Again, so thankful I found this website, I know it's going to help us tremendously.