Thinking it’s weird that his 18 year old will have the master room

So when your kids were in university you "rarely crossed paths"? Mine were back at home for the long holidays, working temp jobs. What were yours doing?

The set up makes sense as this it provides her a study space. I don't think you should move in.

YABU. What a way to destroy relationships with your partner's daughter right from the off?! 🙈🙈

It makes sense for the 18 year old to have the bigger room. Teenagers use their bedrooms far more than adults do. It's their sanctuary. And that will be particularly important to her with you moving in.

Oh and please please do not sell your house. I suspect this relationship is unlikely to last

How on earth could you ever think you were reasonable!?! You’re moving into her home and you want to take her room! I’ve heard it all now! I’d be having second thoughts if I was him.

No way OP. Sounds like you'll have plenty of room in the house anyway. Marking territory with an 18yo isn't a good look. She's old enough to figure out who pushed for the change, to resent it and resent you. Teens and early adults view their rooms as sanctuaries. Let her continue to self contain for her privacy and your peace. She's an adult now so this also feels really disrespectful. She's presumably been given privacy from an adult man. You're not male but you're hardly a familiar presence in such close quarters.

If I were the 18yo I would also refuse. I'd be telling my dad how much lower my opinion was of you, too - and of him if he gave in to you. Assuming you're in it for the long haul with her dad, can't you wait for her to move out fully? Even with more adult DC staying home, she may not.

Is her name Cinderella?

I have to be honest if I was moving someone in and they said this to me, it would be red flags immediately. Yes, you are joining the home and should feel like you are. But this is and always has been his daughters home. I'm gobsmacked. It screams that you think she should change for you.

I simply can’t imagine why your kids would’ve wanted to leave home at 18!

Speaking as an adult stepdaughter whose stepmother moved into our family home, (our father was widowed) it causes resentment. They should have bought a home together not changed my mother's.

And if I'd been turfed out of MY room to accommodate another woman it really wouldn't have gone well

You are not going to last long with your attitude towards his DD!

Leave her alone and your DP has made it clear her room is off limits!!! I bet you feel like you have egg on your face after asking him to turf his DD out of her room.

The entire house will be hers too in the future.

You are being grabby. Grabby. Grabby!

Then count yourself extremely lucky that you’re going to live in a house you could never in a million years afford and keep your mouth shut.

You’re not even in yet and already acting like lady of the manor.

You’ve fallen on your feet then, haven’t you OP? And now you want to call the shots. Deary me.

Taking yourself off the property ladder seems like a bad idea in these circumstances OP. Can't you keep your current home?

What are you doing with the funds from your house sale? If you split up, what will you be left with?

Well, does she have a job, and pay rent, since this 18 yo is an "adult"?

Cannot agree as your statement is backwards.

Respect of an adult in a parent's home is expected from children, teens and young adults either until the adult EARNS DISrespect, OR the parent tells their child the adult in question is NOT worthy of respect.

Children cannot be allowed to decide whether to respect an adult! They are to be taught to RESPECT adults from age zero.

WOW, no wonder teachers are having such a hard time with discipline in schools today!

Parent: "You get to decide to respect your teacher today, IF your teacher earns your respect".

Parent: "You get to decide to respect the law or the policeman". Ridiculous.

You teach them FIRST to respect ALL adults and later, as they mature more and more you let them try to decide who is worthy of respect, because they need more sophisticated analysis skills and good judgement in order to make such decisions.

And of course you teach them what people are not to be respected for 18 years: thieves, bums, child molesters, etc, arsonists. And you teach respect for those positions to be respected: (The President, Generals, Clergy, Prime Ministers...bosses who sign your performance evaluations....😉 ).

My kids could dislike some adult for some reason, like the lady next door who baked terrible biscuits and had bad breath; but they still had to respect her whether they liked her or not, because she was an adult figure in their lives.

Sadly a lot of people don’t care about their children, so get rid the moment they turn 18. They just seem them as an inconvenience and an unneeded expense.

I'd wait to move in until she leaves.

Likely that her new room at her partners is already bigger than the one in her flat anyway but she wants more.

What makes you think you can dictate?

Why can't you be happy with what you've got?

You're lucky she's accepting you into 'her' home.

Watch yourself.

I agree with others - leave the rooms as they are. But what leaps out at me is that you're selling your home to move in. Please don't do this, it leaves you so vulnerable. I know someone who did similar and to cut a long story short, when they split up she didn't get any of that back and had to start again with buying a new property.

Don’t move in. You sound like a vulture. You’ve seen something that is not yours. You want it and would take it. Only it belongs to your partner’s child. It is not up for grabs. Major red flag that you cannot see how wrong your thinking is.

I lived at home til I was 25 because I liked living there, it suited me while I studied & I get along well with my parents. I also had the master bedroom, which was my parents choice. If they’d divorced and my dad had brought a new woman into my life who had tried to push me out, I can guess which one of us would still be in his life today.

It's his house. Maybe OP needs less clothes.

Your update is grim… it’s all about the money money money. I feel sorry for the dd.