(But let's not give up the goal of getting your loved one into treatment!)
Reviews of psychotherapy treatment outcome studies show that: 1) Therapeutic alliance (the largest influence of all) accounts for 5-9% of treatment outcome variability and 2) Evidence-based treatments (vs. placebo) account for only 0-4% of treatment variability.
However...according to Wampold and Imel, authors of The Great Psychotherapy Debate, it appears that about 86% of variance in treatment outcomes can be attributed to factors outside the therapy room!
That would include factors at home and work/school, as well as in groups, organizations, institutions, and other areas of social support. This would make even more sense regarding personality disorders in which identity and interpersonal dysfunction is the core problem. Outcomes could be made better--or dysfunction could be sustained--as the result of factors outside the therapy room.
So I have a hypothesis: Remission and recovery outcomes for personality disorders can be vastly improved by:
Training families in effective social, emotional, and communication skills
to improve self- and interpersonal functioning and
Providing supervision to on-going support groups of trained families.
This just might be an approach that is not only complementary to therapy, but may actually lead to improvements in personality functioning even without therapy!
I am not suggesting that a parent or a spouse should replace a therapist. However, I think it is fair to suggest that a family environment with a higher level of self and interpersonal competencies may account for far more improvements in personality functioning than therapy alone!
Wiser Minds is our own live experiment: On-going "supervision" and mutual support among trained families via chat groups. Participants are loving it! Genuine change occurs slowly, sporadically, and inconsistently. However, families are, indeed, moving toward improvements in the emotional and interpersonal wellbeing of everyone.
References: Wampold, B. E., & Imel, Z. E. (2015). The great psychotherapy debate: The evidence for what makes psychotherapy work (2nd ed.): Routledge/Taylor & Francis.