Hello; thanks for the query. Short answer is its absolutely safe to let her drive provided she is not engaging into drunk driving or driving under influence of some illegal drug!! What we need to understand is personality disorders(PD) can not be equated with serious mental illness like schizophrenia where a person while acutely ill may lose a certain judgement for a while but not always! On contrary, PD should be considered as an extreme form of behavior which defies common societal norms, brings significant distress to patient himself/herself & his/her near ones & hence needs modification. PD can not CURED by all the plethora of medications you have mentioned in question (I wonder why she is receiving so many of them for!!); rather there is a form of talk therapy known as dialectic behavior therapy (DBT) devised by Psychologist Marsha Linehan & colleagues. DBT is usually given by Psychologists & Psychiatrists. Hence find out a Psychologist qualified to give DBT & encourage your niece to enroll there. If she is willing for a change in her current state of life; I am sure DBT can work wonders for her! Hope this helps. Good Luck