PG, you andDH need to sit down and make a list of your rights and options as well as your legal responsibilities. It needs to be on paper. Have lots of paper, lots of time and lots of coffee.
You need to work out what you CAN do (and she can't refuse) and what happens if/when she fails to comply. Because right now, you and he are both saying, "She is done!" when in fact, if you are not legally permitted to throw her out, she is NOT done, not by a long shot. Don't threaten to throw her out unless you know you can legally do it.
Find out what you can do for someone who refuses to take their medications. If you CAN force the issue of "my way or the highway" then it's time to supervise her taking her medications, methadone clinic style. At a methadone clinic the addicts show up for their dose, get given it in a cup, are watched while they take it and then they have to open their mouths wide to show the stuff is gone. Some addicts will hold the methadone liquid in their mouths given half a chance, then go outside, spit it up into a cup then sell it to someone who frankly is far too desperate to care where it came from.
With pills, she has to open her mouth and you probably have to yourself run a finger inside her mouth between cheek and gum, to make sure she hasn't tucked it in there. Then make her sit with you for 15 minutes to ensure she doesn't go stick her finger down her throat. After that, the pills will at least be partly in her system.
The trouble with this, is you need to be able to enforce it. And if she can legally refuse her medications, I don't know if you can enforce it. You can make her presence in your home conditional on her being on medications, even if she is refusing treatment, but you can only do this is you are legally allowed to remove her from your home. You need to be able to say to her, "We can make you leave. We want to make you leave. But you may stay, on the following conditions..."
But if you MUST provide a roof over her head until she is 18, you're stuck.
Find the currency. Find what is your legal responsibility, and make that the baseline. Nothing more. Absolutely. Except for requirements met. And the first requirement is - take your medications. Let us supervise you taking your medications.
Forget college. If she is like this now, what on earth do you think will happen when she goes to college, away from home, away from supervision? If she own't study at home to get into college, why do you think she would study once she got to college?
Before a kid is ready for college, they need to at the very least be self-motivated. She's just not there. And sending a kid like this to college is a recipe for destruction.
It is a little different in Australia, although increasingly parents are forking out for their kids' tertiary study. Frankly, I think it's crazy, because there is less ownership if it comes too easily. You need to be REALLY sure that this is valued by your child. Otherwise they should just go out and get a job, work from the bottom up and go to college later on, perhaps, when they have a better idea of what they want and how to get it.
Right now, your daughter seems determined on throwing her life down the gurgler. Given what you are saying in this thread, the previous one about the loser boyfriend makes a lot more sense, sadly.
What does she see in him? No, it's not just that he's a loser. That is NOT what she sees in him. She is accepting this in him because he has something else she really, really wants. I suspect this is drug supply, on a multiple level. She needs money for drugs, and she needs drugs. He could be providing a means to obtain both. He could even be her pimp. Why was he beating up that guy? Why was he so desperate to evade the police? What was he carrying in the car? You only saw the stuff able to be released - what do the police know that they did not release? Have you talked to the police about your concerns?
How thoroughly did you search her room? Now go and search the rest of your house. Focus on the garage or any area less scrutinised. If you have animal pens outside, check in there too. Check in the garden sheds. Check in the car. Look under the beds, under the mattresses.
If she is abusing drugs (including prescription medication) on top of her other problems, she is heading for big trouble. You need to be very careful to not enable this. It is easy to do. I would suggest that now, as fast as you can, make contact with Narc-Anon or similar groups and get their advice. Then act on it.
I think you are in way over your heads, but there are lifelines around to get you out of the shark tank. Then you can begin to shark-proof your home.
Marg