Well.... encourage her NOT to do so without speaking with her psychiatrist first. The doc will help the patient evaluate and come up with a plan if needed. If the plan fails (which has often for me)- then the doctor knows and can help with another plan.
For the ones weaning: It's a bad idea to wean and not tell anyone. One day- a friend may find you in a closet, holding a knife in paranoia. Or you may crash and decide to take a bunch of pills, blow your brains out, or jump off a bridge. Seriously, you can go from feeling happy and healthy to something dark and painful in a matter of days.
Figure out your go to person- the person who sees you or talks to you regularly. The person who can help gauge if you are messing with your meds and need help.
And if you are the family or friend, think about what it means to be the go-to person and offer if you can.