Hello ReadyPlayerOne: Thank you for bringing your concern here to PC. I see this is your first post. So… welcome to Psych Central.
We here on PC are not able to offer professional mental-health-related advice. Plus I'm not a mental health professional. So all I can offer you is my personal non-professional perspective with regard to the situation you describe. You didn't mention, I don't believe, if your family member has actually been diagnosed as having delusional disorder. What you describe in your post made me wonder about the possibility of schizophrenia. But of course, as I've already mentioned, that's just my personal non-professional opinion. So I may well be wrong.
The point though is, I believe, without knowing specifically what your family member's diagnosis is (beyond OCD, mild body dysmorphia and various personality issues) it may be difficult to answer your questions to any degree of certainty. And the only way you'd be able to get a diagnosis would be for your family member to be evaluated by a mental health professional, which it sounds like is unlikely. As such, my personal opinion would be that what you & your family may need to do is to simply take whatever steps are necessary to protect yourselves given the behaviors you are observing at the present time.
I know you mentioned you've read all you can about delusional disorder. So perhaps I can't give you any additional references that will be of help. However here are links to 10 articles, from Psych Central's archives, that I thought might be of help or at least interest:
Delusional Disorder Symptoms
10 Things You Should Know About Delusions | Caregivers, Family & Friends
10 Things You Should Do With Someone Who Suffers Delusions | Caregivers, Family & Friends
8 Ways To Cope With Someone Who Has Delusions | Caregivers, Family & Friends
Coping With Your Loved One's Delusions | Caregivers, Family & Friends
https://blogs.psychcentral.com/careg...dium=popular17
https://blogs.psychcentral.com/careg...dium=popular17
https://blogs.psychcentral.com/careg...dium=popular17
https://psychcentral.com/schizophrenia/
https://psychcentral.com/schizophrenia-guide/
My best wishes to you & your family. I hope you find PC to be of benefit.
