Is it possible to use magick to cause someone else to become possessed, in that the demon is offered control over that other person’s body?
This is a bit of a complicated question.
Forced possession is possible, yes. However, it will result in a battle of wills and there is no guarantee you will come out on top.
You do not have the right to offer someone else’s body, so therefore, their will and their Spirit can and most likely will, fight off the possession. One of the rules of possession is the demon has to be accepted by the one that is possessed. Even the Catholic Church recognizes this, and understands that an exorcism is useless if the person refuses to reject the spirit.