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

You must tell your DP that you want the master first thing today. Make it really clear how you mean to go on. If he's a decent chap all necessary decisions should be made by lunch time.

Why are you selling your house? Where will you live if the relationship breaks down in the future?

If you were all moving into the house new, absolutely.

But it's already her bedroom. To move in and immediately turf her out of her room is giving Wicked Stepmother.

If this is a long term house then you can move into that room when she moves out.

Is there a basement by any chance ? Or a room beneath the stairs ? Maybe you could keep her down there to do laundry and earn her keep without getting in your way. That way you’ll not only have a walk in robe but your clothing laundered and mended too. It will also send a clear message of who the new matriarch is.

This post reminds me way too much of my childhood and how territorial new wives etc are especially when there’s prime real estate and wealth involved… oh and a wir.

If you want to mark your territory properly you need to remodel the house and redecorate in an entirely new style. You’ll also need to ensure he replaces the mattress other women have slept on. Make her knock on the door and replace the locks. Speaking from experience.

This "master bedroom" is just nonsensical estate agent speak. She has the larger bedroom. So? That was agreed on, it's her home.
You're moving in, you compromise, although I can't see what's wrong with your bedroom.

Agree. Why not rent the house you live in out ? You’ve certainly done well for yourself. Quite a leap.

I think it's weird that you think you can move in and demand that his daughter loses her room. What sort of relationship are you trying to have with her

Don't sell your home OP, rent it out untill you know living together will work out or you will be stuck if the relationship fails.

Don’t pit yourself against his daughter. You’ll lose!!! You are moving into their home. Be humble!!

….and keep your own house.

So you are doing the territorial 'I need to win' thing

Yeah can see this one lasting

This is why stepmothers get a bad reputation.

You’re jealous of his daughter and before you’ve even moved in you want to kick her out of her bedroom! You have no thought to the fact that it might be strange for her to have you move into her home.

Calling it weird as if she’s doing something wrong when her having the biggest room is the choice your DO made, says a lot more about you than it does her.

Tread carefully @grizzleGrazzle

Don't make this your hill to die on, particularly as it sounds like it's a huge house with more than enough room for everyone. You are coming across as the evil stepmother sidelining Cinderella from her home.

Also why are you selling your property? I wouldn't do this, at least until you are married. What happens if it all goes tits up?

And in a short while will you be suggesting that she moves out to live in halls of residence and can only return home for Christmas?
I really can't believe this attitude you have. You haven't moved in yet, but you want to upset his daughter, and him, and all for a walk in wardrobe.

I agree about renting out your own property! Wow, what if it all goes tits - you'll have no bedroom at all then!!

I do understand what you are saying but for the sake of trying to build a good relationship with his daughter no you can't swap her room, not at this stage. I think you need to really think about the psychological impact of you moving in to make this relationship work

Ok well no of course you can't turf her out of her room, that would be dreadful behaviour and would absolutely set the tone for the rest of your relationship. That aside, it makes a lot of sense that she has that room when you think about the fact that as a young adult, she would likely spend a lot of time in there... studying, watching TV etc. It's important she has priory proper space, whereas you and your partner will use the rest of the house, presumably there is at least one lounge, you've already mentioned an office etc. I would also be happy for my daughter (or step- daughter) to have this biggest room in this situation.

Hands off, greedy. Is this really how you want to start your new life? Squabbling over who's got more? You'd be better off keeping separate lives, you don't sound like a willing sharer.

My son has the biggest room as , like others have said, he spends a lot of time in there , plays music and his mates round , I only sleep in my bedroom and use the lounge or dining room the rest of the time. If I met a new partner I wouldn’t consider turfing him out . You can maybe swap rooms when your partner’s daughter moves out .

Sounds like your DP might benefit from some MN wisdom:

When someone shows you who they are, believe them the first time.

Fanny lodger.

The only post you replied to was the one agreeing with you.

Shows what type of person you are really.

Nailed it.

Way to make his daughter resent dad's girlfriend, OP.

Quite apart from your rather antiquated views about the adult-child pecking order and the use of the dreadful term 'master bedroom' (a 4-bed detached in suburbia isn't Downton Abbey, notwithstanding all estate agent-speak), your attitude really doesn't bode well.

So you want to move in and then turf his daughter out of her room? Absolutely not. That’s how you make enemies.

Well that actually makes perfect sense

Ugh. Do you want a good relationship with the daughter or are you looking to establish your new role above her in the house?

I think you prefer the house more than your relationship.