Thanks for your speedy reply.
First - it would be inappropriate (and unethical) for me to make a diagnosis over the internet (and across the Atlantic Ocean). Please understand that this information is not diagnostic in nature - but just some initial steps.
If you believe having a diagnosis would be helpful (and it *is* the first step in moving toward treatment), then I highly recommend that your sister see a Licensed Mental Health Professional (LMHP). Given the complexity of the problem you describe, I might recommend she see a psychologist - who would employ extensive diagnostic protocols to better understand your sister's functioning.
That being said... you should know that Narcissistic Personality Disorder (NPD) is somewhat controversial. You should know several things about the field of psychology/psychiatry:
1. The "big book" used for diagnosing mental disorders is the Diagnostic and Statistical Manual of Mental Disorders... and has undergone a number of revisions and changes over the years.
2. While there are still discussions and arguments about the material contained in the DSM, none is more controversial than those disorders located on Axis II (so-called "Personality Disorders").
3. You should understand that there are licensed mental health professionals who do not believe in the concept of "personality" and do not, therefore, believe that a personality can be disordered.
4. Even for those who find sufficient evident for "personality," the disorders listed on Axis II can be controversial. Besides difficulties with diagnostics, if personality is an immutable trait of an individual - how can one treat it? If one were to diagnose an individual's entire personality as "disordered," what could one do to "re-order" it?
Obsessive Compulsive Disorder (OCD) is a complex Anxiety Disorder that involves, as it suggests, obsessions and compulsive behaviors. Someone who obsesses about the past or "gets stuck" thinking about something isn't necessarily OCD. Unlike NPD, OCD is an Axis I disorder.
Research has consistently demonstrated that treatment plus medication is more effective than medication alone or treatment alone for a majority of Axis I disorders. Further research has shown that Cognitive Behavioral Therapy (CBT) is the most effective form of psychological treatment/intervention.
A licensed psychologist/psychotherapist with specific training in CBT modalities would be able to address your concerns. I would encourage you to find a licensed mental health professional with whom to work, employing CBT. Referring to a psychiatrist for medical treatment is appropriate if you are interested in pursuing this approach.
Again, the mantra of years of research says: medication or treatment alone is not as effective as both working in tandem. Some research has also indicated that insight-oriented talk therapy is counter-productive with some forms of Axis I disorders... it actually exacerbates the condition(s). So, seek out a CBT therapist who will provide targeted, efficient, and effective therapy - not someone who signs you as a "lifer." If you're going to a therapist for years, something about the therapy isn't working.
SO: I will return to an adage I learned during my residency... "If you hear hoof beats bearing down upon you, it's far more likely to be a horse than a zebra that's coming..." The same is true with mental health disorders. NPD is highly controversial, very rare (if it exists at all), and some would argue, untreatable. A host of other disorders (that *are* treatable with good prognoses) could explain the very same behaviors used to describe NPD.
Finally, the reason I asked about legal involvement is only this: you may be able to get your sister into treatment, but that does not mean that it will necessarily get her to stop her untoward behavior in your family. If you are SERIOUSLY concerned that her behavior is harmful to herself or others, or that she is violating the rights of others, then you should call the police and begin the process of legal involvement.
Diagnosis can help understand behavior we find uncomfortable or dangerous. Treatment can help change or reduce behavior we find uncomfortable or dangerous. But if you really want it to STOP - you make have to involve the court system. I realize that this will be very painful for everyone involved - but if her behavior is rising to such a level that you fear for the safety of others - it's time to involve the police.
Thanks. I hope you're well and that this was helpful.
* FEEDBACK ENCOURAGED. Please contact me prior to leaving negative feedback so that we can resolve the matter. I am eager to work with all JA clients to provide them with useful/helpful answers. Thanks again.