So what's her plan? Working part-time is not a plan. Does she intend to go to school/college/university? She either works full-time and looks for her own place to live or she's in school full-time. Do not tolerate anything less.

Why did she move in to your home? Were you asked your opinion or were you bulldozed?

I could scream with you. 

My bio son came home in his mid 20s for a while. He NEVER complained about what I cooked. He ate what was on the menu, he cleaned up, helped with yard, errands, etc. It was a short term stay with him advising of move out date. He was a "plus" to our home while he was here.

I've seen how DH coddled his kids when they were young. I've also watched how he's allowed them to treat me over the years. No way in hell will any of his kids (now all adults in their 30's and 40's) be allowed to live in our home (and there is one, at age 30, who would love to plop here lazy azz here). I've been clear...he wants them to move in with us, he'll move out to a new home with his crew and it will be the end of us. I've tolerated enough BS for 12 years. The past 5 have been peaceful with him seeing them away from our marital home. I'm not going backwards.

So, my advice is to get with your DH, have clear expectations of the ADULT child in your home with a DEFINITE departure date, then your DH can meet with his kid and give her the information. And if he can't do that...then you have decisions to make. You have a voice in that home, also. Don't let him get away with "that's how kids are today" crap. Kids are like this today because of enabling, lazy parents...not because it's the right way to be. SMH

Was SD always there before emancipation age? Dad and bm splitting custody with no child support given to BM? And now, this is just an extension of that?

OR this is the new arrangement now that child support ended?

Edit to add---THIS IS NOT how kids are today. 

Why did you allow it?

There needs to be some sort of plan or end date. Did DH let SK moved back in without consulting you? My SD is 13, but I have already had the "launch" talk with DH. Saying SD needs to be doing something productive (school, job, etc) when she is 18, or she is out. 

I get the need todothe "primal scream"out into the "void" of anonymity, but we tend to go into problem-solving mode here. Welcome to the site, read around and you will find that you are not alone.

Without additional information about your sitch, Ill just say that you arent alone - - it seems a common theme for bio parents to have those bio love goggles on and cannot see how annoying and irritating their spawn, er, kids actually are.

Her many health "issues" and constant need to be up your collective b@tts could be seen as desperate bids for attention. We have a toxic trolll BM and I call her a "disease chaser", someone who goes to multiple doctors for mulitple "issues". Just everything. Toxic Troll plays the long game, hit her head over 5 years ago on some monkee bars at the school she was working at, and now almost 5 years later, multiple lawsuits later, recieved 21k settlement! She still gets "child" support, and still qualifies somehow for low-income housing for a 2 bedroom apartment in a nearby beach town.

TT Bm has created two children that are also looking for diseases to have - most recently lupus imaginaria. Then the allergies and now "heart palpitations", anxiety "attacks". It never ever ends, because they dont want it to.

Your partner and you need a conversation. But you need to couch things a certain way. Instead of "brat", say enabled. Tell him of your desire to see her grow into a strong self-sufficient healthy young lady...etc.

And then lay down the law of what expectations are going to be as regards your time alone, her time, and what she will be doing in the future as to schooling and/or working.