Hello vsw: Since this is your first post here on PC, welcome to Psych Central. One additional forum, here on PC, that may be of interest would be the relationships & communication forum. Here's a link:

https://psychcentralforums.com/relat...communication/

I'm sorry I cannot be of help with this unfortunate situation. However, here's a link to an article, from Psych Central's archives, that (hopefully) may in some way be of some help. It is part one of a two-part article. However it appears part two has yet to be completed or at least I couldn't find it:

Understanding Manipulative Mind Control and What to do About It (Part 1)

As has already been observed, assuming this person is an adult there may not be much you can do. I don't know if you've tried having a heart-to-heart discussion with this person regarding your concerns. That might be one thing to try. Here are links to 7 articles that discuss how to prepare for, & have, difficult conversations:

5 Ways to Prepare for a Difficult Conversation

Tips for Talking About Tough Topics

Effective Conversations About Difficult Issues | The Emotionally Sensitive Person

https://blogs.psychcentral.com/anger...kward-moments/

https://blogs.psychcentral.com/child...ortable-truth/

https://psychcentral.com/lib/how-to-...ets-defensive/

https://blogs.psychcentral.com/anger...-conversation/

My best wishes to both you & your loved one. I hope you find PC to be of benefit.