Work with your DH to put together a list of options for her....all in the spirit of helping her launch (rather than keep her out of the house).  

Examples: college, military, work full time job, get a job on a cruise ship. Laying around fanning herself is NOT an option.   When my son was given options and made to choose, he grew up.

I don't want a grown adult mooching off us with no sense of responsibility or accountability.

Have you told your SO this? You need to have a conversation with him, then he needs to have a conversation with his daughter.

I would set a hard boundary with you DH and make sure he agrees to it. 

No adult child lives in your home unless... 

Then list all the needs. Full time student, job, license, vehicle, contributions etc. 

And then set a financial boundary. We do not support adult child unless and limited to... 

And list it out. We do not pay extras. We do not contribute unless it's matched by adult child etc.

If you don't set expectations you will regret it. And these expectations will limit arguments as it has already been cleared. 

She doesn’t like people. She has no transportation. Well boo hoo. That’s not how the world works. 

That young lady needs some serious expectations and a plan to launch. I don’t mind helping our adult kids as long as they are working their asses off in a job or in school or both. But I refuse to support lazy entitlement. 

Sort is the wrong place for her... does she even know group assignments are common in alot of units, interacting with other students is something that helps you succeed at uni.... if she doesn’t like interacting with live people, maybe she can become a mortician, forensic pathologist or one of those drs who does an autopsy. But you have 1 problem!!! Sd doesn’t appear very bright or committed... at least with dead people she doesn’t need to talk....

ahhhh skids why are you often such dickheads??? Oh right because mummy and/or daddy couldn’t grow a pair of f*cking tits and balls and woman/man up raising quality kids who are equipped to handle the real world and be decent humans...the result.... yup spoilt ass selfish i’m the centre of the world brats 

if uni is too much of an effort she could become a gardener... you know sweep, water plants etc but then again that involves actual work which skids by nature tend to be lazy and incapable of doing work because apparently we exist to serve them. 

Looks like she’ll be a useless dole bludger living off welfare payments.... the dream hey!! There goes peoples hard earned tax money

I would work with your DH to come up with a contract. Something that has timelines and expectations. There are tons of options including college, trade school, certification programs, military or basic jobs. She needs to choose. None of those include living at home for long after HS! She needs to sign and be held accountable. Make her sign a lease at 18 for rent. You can always hold the $ to gift her when she launches, but she should be responsible for her life.

I promise you - if she moves back in it will cause endless problems.  She won’t leave, work or do anything other than make you upset.  When you finally blow your top, you will be forever the bad guy. So nip this in the bud.

Semi adult spawn (HS graduate) SS-26 knew the requirements to remain in our home after his 18th  BDay.  He graduated from HS 3mos before his 18th BDay.

He had to be a full time student, working full time or doing both part time.  He chose none of the above. So we turned him into our live in full time beck and call boy chore bitch.  We worked that  kid’s ass off.

We created an escalating intolerable burning platform that drove him to enlist in the USAF.

He had a choice, chores, the streets, or launch.

Set the stage and clear expectation of a life of abject misery for SD upon graduation,  She will learn.

Sounds exactly like my stepdaughter.  Everyone coddles her . No one makes her accountable for her actions or to be an adult and do basic adult things like working or driving... DH is the worst for enabling her. I cannot see her ever being an independent adult with a job, a car , basic functioning for her age. She's functioning at the level of a twelve year old.

How about if she doesn't go to college and/or getting a job staying in your home doing absolutely NOTHING will not be an option and she can take that nonsense to her mother and she can deal with a coddled child......

You need to have a serious talk with your H because this will fall in your lap with no solutions or consequences.

my husband and I built a house together 7 years ago when my SS was 15 years old.  I had been in my SS's life since he was 13 years old.  He had asked us if he could move in with us just after the house was built (he was 15 years old).  We said ok and once he was moved in, I told him that there are rules to living under this roof.  For the most part, he has been good with doing what is asked of him.  He "forgets" sometimes and that makes me cringe and I get him on whatever it is immediately.  He is now 22 years old and just finished up college (early) and will graduate in May 2019.  While he was in school, I made him get a part time job.  I really believe that if I wasn't there, my husband wouldn't have made him work (hubby is very laid back).  Now, my SS has a his first full time job in what he studied in college and seems to be doing well.  I think boundaries need to be set and rules put into place.  My SS has issues with me because I lose my sh*t when he "forgets" to do something (like leave the garage door open ALL DAY because he didn't see that it fully went down) ----   and I seem to have to "remind" him to do things and I feel  that a 22 year old shouldn't have to be reminded.  I make him accountable for all of his actions and he says that I rule with fear and that is wrong... I don't rule with fear... I tell him the truth:  If you don't live by the rules of the house, please go live with your mother or find another house to live in, period!!!!!    The problem with alot of today's young adults is that they feel that they are entitled and don't want to work for anything.  My SS has told me that some of his friends, at 21 years old, DON'T have their drivers license yet!  What?!  Their parents still drive them around.... Talk about coddled!   If my SS spends too much time in the house (pretty much in his room all day playing video games), I tell him to get out and find something to do.  I have been telling him that since he was 17.  I was not going to have him hanging out playing video games all day.  That was another rule.  I didn't want him to become some anti social being by not having any human interaction and turning into a recluse or god forbid, a psycho.

So, basically, he has issues with me because of my ways.... I'll admit that I have been tough on him as that is how I was raised and although my parents were super strict and it was painful some times, they raised me to be a very independent woman who doesn't ask for anything from anybody.   I just hope one day, he will see the responsbilities I have taught him and be grateful.  (Note:  His mother is around but an alcoholic and pathalogical liar with bipolar disorder that she refuses to get treatment for, so that relationship is not good)

Thank you for listening to my vent!  (or reading my vent!). 

Before SD is allowed to move in with you, you and DH have to establish the ground rules. Prepare a letter of agreement for her to sign which spells everything out. Also outline the consequences. If she refuses to sign  she can't move in. If she doesn't follow the rules as agreed - she's gone. If she is not going to school, then she has to work and she has to pay rent. This is how the real world works. Years ago (before we were married) my SS moved back in with DH because his roomate wanted privacy and he owed a lot of money on credit cards.He was 23. I told DH that he should charge the kid rent. BM went crazy. SS was furious that he had to pay to live in his own room. However, it was a great lesson. It taught him that grown ups have responsibilities and having food in the fridge, lights that turn on,  and someone to do your  laundry is not free. When SS paid off his credit cards and had a stable job (it took about a year) he finally moved out. DH surprised  him with a nice check consisting of all the rent he had paid. It was forced savings and a great lesson.