Thirty years of practicing psychotherapy here.
If she can handle matches, lighter and lit cigarettes, she should be able to handle an ecig. I wouldn't worry too much about the subclinical level of Mao-inhibitors in cigarettes - they're not even significant enough carry a warning re contraindications (very significant in clinical doses). She's almost certainly already getting a cocktail of big guns antipsychotics and other psychotropics -
tobacco MAOs most likely an insignificant drop in the bucket. But check with her psychiatrist yada yada.
If she needs to be supervised when smoking (and she obviously does in use of the patch, unless she stopped that when properly instructed), then the same would apply with ecigs. She hasn't burned the house down, right? Nicotine overdose would be a concern if she likes them very much. Otherwise I think it's a workable idea, though that's not a professional opinion as I don't know her.
I'd very much like to see ecigs introduced into psychiatric units and hospitals. They dole out patches, but they're not very effective, and highly anxious patients suddenly tossed into withdrawal must wait for whenever the designated "smoke break" occurs if they're at a hospital that allows that on the grounds at all. This usually becomes a behavior management tool, which I find deplorable. "If you don't calm down, then no cigarette break." Very cruel and irrational, as are many practices in this ignoble profession. (You don't want to get me started.)
As for drinking the
juice, schizophrenics don't usually lack that sort of judgement, if the situation is explained. If she's suicidal and told that it's poison, however, I'd not have it around. I'm sorry for the tremendous difficulties your family has been having - it's a tough one.
We are all self-medicating with nicotine.