Of course you can't - people can't really control other people - can't make them do things. You can manipulate the heck out of the situation and the environment - but you can't control other people.
I seek my husband's control of me - that's pretty well established at this point. But that isn't total control. All people retain their free will at some most basic level, this is as it should be. And it's a discussion for another time. Right now I'm running into the downside of this whole idea.
Right now i'm concerned about family members who i love very much, not my husband and children, but family i love and can't influence (or control) enough to really help. In movies or TV dramas, all imaginable circumstances are set up to work against the protagonists, their own personal flaws or tragic decisions have fed into the crisis, and the drama plays out like an inevitable train wreck. Except that in movies or on TV some small twist of plot or sudden enlightenment and change of course, or unrealistic last second reprieve gets worked in and all is saved in the end; the protagonists only shaken and slightly scarred.
In real life, real life happens. The circumstances of life move on, oblivious to the people being impacted. The people involved continue to live and make decisions the way they always have. Health deteriorates with age. And there is no deus ex machina.
There are answers that would help, there are many many people trying to help, there are many people expecting me to be able to get them to accept this help. I know it is an arrogance to think i (or we) know better than they how to run their lives - that doesn't make it less true here, just less comfortable.
In the end, we can't control other people. We also can't stand by and watch those we love sink into the quicksand of their lives.