living with BPD sister. advice? intervention?

hello

i am soon to be living with a my sister with borderlinePD and bipolarMD.

she suffers from alcoholism, prescription/illegal drug addiction and sex addiction. she has attempted suicide many times and often makes suicide threats. i am going to try my best to convince her to go to an inpatient program, however last time we tried to bring her she was refused entry because she was not clean.

A) does anyone recommend a mood/state where she may be more willing to receive help? i am assuming in her 'lows' as apposed to a manic episode (when she is feeling in control of herself)

B) in the event that she refuses rehab, or is put on a waiting list, what can i do to support her? i want to be there for her, but i don't want to become an enabler or victim of her abuse. as i am also struggling with mental illnesses, and need to protect myself during my own healing process.

thanks so much.
and my heart goes out to all sufferers, i know this must be incredibly difficult. stay strong and best of luck! XX