Ask him flat out how he plans to handle the added bills when she is there. Groceries aren't cheap, lots of showers add to the water bill if you have one, and I'd make it clear YOUR is NOT a flop house for her friends.  If he can't handle your limits then maybe he should move out until she's launched.  It is YOUR house and he needs to remember that.  Adult skids get different rules but she needs to know it's your house too.  She won't be trashing it or she's out.  Be firm on your boundaries. If you make it to comfy for her , she will think she can move in.  If he balks at any limits on her , rethink his motivation for being with you.  Look for the red flags 

Er, I think I would rethink the whole plan.

But if you DO go ahead with it:

1. When she is there, she pays her share of the bills (I assume she'll get a holiday job?) If not, your SO pays two thirds of all the bills when she is in situ.

2. YOU are the house owner. It is YOUR home, not hers, or your SO's either. SD does not have friends staying, or her BF dossing down. If she wants to spend nights with him she can go to his...

3. She needs to pitch in with her share of completing chores. No ifs or buts.

4. Again, it's your house and you don't allow people to walk around semi naked. Your house, your rules. SD needs to respect this rule.

Honestly I would not let them move in, but that's me. If your BF thinks he needs to provide her with a home base for the next umpteen years maybe he should stay in his own place? 

Good luck...

A word on the girl having BF to sleep over: my ex was a hopeless parent with zero boundaries. His daughter would go into town, get trashed and bring home random guys to stay the night.

I said to him.... there's a safety concern right there! How do you know that this guy isn't going to rob the place, isn't carrying drugs or a knife?? SMH still at him for allowing this crap!

I'd maybe pump the breaks on them moving in.  As my dad used to say, 'tangling is so much easier than untangling'.  Meaning moving them in is the easy part, moving them out if things don't work out is so much harder. Unless you are 100% into the idea of the 3 of you living together, I'd slow roll this move in. 

Your BF should be paying 2/3 of the bills (including more for the mortgage) during any time his adult daughter is staying in your house.  2/3 of the residents are in his column, so he should be paying his share.

Before they move in, you should establish house rules.  No boyfriend/friend overnights if you don't want them, and certainly not without permission in advance, full dress required when she's outside of the basement, her room and bathroom are to be kept clean, she's to help with household chores (and if she can't clean up after herself and contribute to the household, then BF can pay more).  I would also make it clear to BF that his daughter living in your house is only for school breaks and only until she finishes school (or would finish school in the ordinary course - she can't be on the 6 year plan).  

Since you have reservations about the daughter moving in, you might want to think about waiting until the daughter finishes school and launches, but if you don't want to do that, make sure you have a good understanding/boundaries up front with your boyfriend, and don't deviate. 

DON'T DO IT!

So, if I'm reading this right, your bf is set to benefit most from this because he is going to rent ot his home at a hefty rate. Why are you going to ask him about bills when his daughter is there? You tell him that he will be paying 2/3 during those months and not the usual 1/2. Anything less is daylight robbery. 

As for your home having more space ... how much space does a couple need? Have you considered renting out your basement instead? Whose idea was it for them to move in with you? The very fact that you're apprehensive about her moving in because of her attitude is a huge red flag. What you usually get is worse than you feared. You're trying to focus on her good points? Don't. Be realistic. Look at her bad points head on. She's been catered to nearly all her life so she's used to getting her way. You are on the point of moving a mini-wife into your home (your bf has already admitted that he can't say no to her). Please do some searching on this site for "mini-wife". This is a potential Hell-on-earth that you are planning.

This is your home we are talking about and you need to stop bending over backwards to accommodate them. You dictate the terms on which they move in and the first rule (in my book) is no overnight guests, none. The second is no parties. If she wants to develop her social life, she does it elsewhere. No coming upstairs without being fully clothed would be on my list. And any transgressions would result in immediate eviction (actually, eviction is never immediate ... think that over, you could be stuck with her for a very long time). Rent will be paid and chores will be done (draw up a list now). She doesn't get to lie around all day for nothing just because her daddy is bopping the landlady ...

What happens if she decides to drop out? Imagine she feels so comfortable living in your basement that she decides to stay indefinitely. And daddy, being unable to lift a finger will just let her be, won't he? Nope, keep your respective homes for the time being. He can spend as much time at your place as he likes but she stays firmly planted in his home.

Take the advice from another poster, hold off on this move until she's finished college and has a job. Where's the problem? Then and only then, make a decision. Anything earlier than that would simply be crazy.

Do not allow yourself to be bullied or persuaded to go against your gut feeling. Please have a good long read of the posts in the adult stepchildren posts.

I agree with the other posters, but especially Winterglow's post. 

You wrote:  "BF's not crazy about her living with us either. He definitely wants her to launch. He's had a hard time saying no to her, probably from not really having had much help raising her--he doesn't say no to sleepovers or gatherings even when it's not ideal for him, takes her to nice places and buys nice things for her, doesn't feel comfortable telling her not to walk around the house (or in public) in lacy bras and bustiers since at this point she has a fit about body positivity if the subject is broached."

Sounds like your BF is guilt-parenting and his daughter has mini-wife symdrome.  My ex did the same with his adult son and his adult son was more like a spouse to his dad, it was creepy and weird.  And it left me as odd man out, which filled me with resentment and frustration.  

I read your previous post also from September of 2020.  I'm concerned for you.  I feel like this won't be a healthy or fulfilling relationship for you.  I know you are seeing the good in him and his daughter, but this situation has red flags written all over it.  From your September 2020 post and then this one, his daughter seems to be pulling daddy's strings and completely running the show.  She wouldn't "let" your BF have you come over to stay the night?  You had to eat dinner with him and then leave because she didn't want you there? I worry that you move them in with you and his daughter will call the shots like she always has. I know others have posted about setting expecations up front, which I agree with.  But in my opinion, you can tell them up front what you expect about living with you and even be stern about it, but I can promise you that once they are moved in with you, things will change. 

I recently left a similar situation less than a month ago.  It started out kind of like yours, my partner at the time moved in, his son followed a few years later living with us full time, and the two ended up acting like a married couple, his son ran our home and I became so miserable that I ended up leaving (long story short, there were a lot of other things going on, but that was the main issue:  guilt parenting).  Once they were moved in, my partner set no expectations, boundaries or consequences with his son, even though he swore up front that he would.  I don't think your BF will ever be able to tell his daughter no or set any boundaries based on your posts. And once they get moved in with you, I am relatively sure things will change... for the worse.  My ex stepson (now 21, almost 22) is so comfortable living with daddy that he has no plans to move out.  Ever.  In fact, at one point in our relationship, his dad was trying to talk me in to renting a home with a large, finished basement "so he can just live with us and not have to worry about moving out.  He'll have his own space."  I think your BF's daughter will become too comfortable living in your home and never move out - and she'll dictate every aspect of your relationship, like she has already shown she does.

Please re-think this situation.  It is not fulfilling to be in a relationship where the adult kids call the shots - I know because I've been there.  Only you can decide what is best for you but please read these posts and really think about YOU and what makes you happy. 

Please keep us posted! 

When I was in college.. once we moved off campus.. I actually had an apartment year round and worked a job local at the college and took a few summer school courses.. why could something like that not be an option?

DO NOT let them move in. 

You are the lady of the house but you wont be when the wife moves in with her daddio.

You have had years of problems with this chickie poo thanks to big daddio kissing the ground she walks on.

Why should he move in, he has his own place. How nice for him though, he can rent it out and make money. You on the other hand will never be fully compensated. I dont mean this just as financial, but also emotional. He is taking advantage of you.

Your quality of life, your self esteem, your outlook will take a nosedive. Why ruin your safe place, your house, just so you can be taken advantage of by your BF and his wife/daughter?

Trust me, I have been you with the DH whose mini wife called the shots, made my life hell, and my DH kissed her arse the whole time.

Do better hun. You deserve it. Blessings

If he's going to rent his place out for a hefty sum he can afford to pay you half the mortagage/groceries/utilities year round, and for four months of the year he can subsidize her staying right where she is at school in a summer sublet.  There is no need for her to move home to save them money and make you nuts!

With the down sides of them moving in, I would insist that your SO pay you 100% of his  usual living expenses at his own home (mortgage, utilities, maintenance, etc..) since those would be the usual and customary costs he would pay to support himself and his daughter in his own home.

They will also be perpetrating that level of wear and tear on your home.

Also, make it clear that SD-19 will not have overnight guests in  your home.  Your house, your call.

He/they may not like it, but... tough shit.

IMHO of course.

Or, go with the advice above that daddy can sublet her a place for the summer.  She is not a minor and the summer sublet solution minimizes the risk to the longevity of your relationship with your SO.

In fact, I would do both the full contribution of his usual monthly living expenses plus he sublets the SD a place for the summer.  He would have to house them both if they were not living with you, so, you should get that $$$$.

I agree with you - at the first transgression, out she goes.

Sadly though, the Dad appears to be very non confrontational and the daughter is totally in charge of him. I doubt that he would ever enforce any house rules.I just think this whole idea is a recipe for disaster.

IMO it would be better to just keep the status quo, and see what happens in the SD's college years. See if she becomes independent and has her own life.

And if she grows up and lets go of the idea that she owns Daddy.