Are our friends being cheeky?

Your not being unreasonable at all. Unfortunately sometimes adults may not have their own social lives due to circumstances but that doesn't mean that the parents have to include them in everything. My 40 year old brother doesn't have many friends and see his dad as his best friend, and my dad's friendship group have seen my brother grow up and happy to socialise with him but my dad also makes sure they have times where my brother isn't around as it does change the dynamics of a group as has been very clear that their annual lads holiday will not include him as that is for him and his friends. Your friends need to be more firm with their DD, maybe the DD is coming round for company but no reason she can't spend the weekend round at their house but spend the sat evening home alone watching telly etc. Doesn't mean she has to do everything the parents are doing. The parents need to say yes DD your welcome here for the weekend but we are out sat night so youll have to sort yourself out then.

Hey everyone! Let's use this thread as yet another excuse to attack childfree people!

Give me strength.

WTF indeed.

WTF ???????

They are probably composing an AIBU between themselves that goes "Should this woman have invited our DD when she knew she would just sit in our house alone otherwise?"

If so, they would BVU. It's a 40yo woman in a house, not a baby in a hot car. Aside from the dramatic suicide-watch scenarios - in which case they should all stay home - there's no reason the DD can't cope alone in her parents' house. And no reason why her parents' friends would invite the DD (effectively a stranger as described by the OP) to a dinner involving personal conversations.

Agree. I’d rearrange for a different day.

I agree... I think an excuse about extra numbers would be quite offensive and come across as you not liking the DD. From their point of view.. they've hosted several times and you've all got on OK.
I think that if their DD has said she's visiting, they probably feel awkward leaving her at home alone whilst they go out to see the friend she's had dinner with at theirs several times, and so if you said no - they'd cancel anyway.

As she only visits at weekends, try inviting them during the weekdays.

OP didn't moan that the DD was at their house when she went over to visit, she just doesn't want the daughter invited over to her house. If your parents aren't inviting you to their friends houses, it's very different scenarios

Well if myself or my brother happen to drop in and we don't know my parents have their friends over, they look really annoyed and will say things like oh I thought it would just be us. Because I know they are like that I don't visit when I know they are there, but my brother who is slower to take the hint, will not just automatically leave early when he sees my parents with the visitors who are quite possessive of their time. Usually the female of the couple will then phone my Mum a day after their visit to express disappointment that the "family" dropped in when they were there.

I think the OP should just file this under 'people can be a bit weird at times' and tread carefully
Why should the OP 'tread carefully' and acquiesce to the CF who don't seem to think that they should be.polite and 'tread carefully?'
Are all those who think op should accept the friend's rudeness, are you either the CF who think others should do as you want, or walkovers who'll do what others tell you?

Surely a message to say 'no worries if you're busy this weekend with your daughter, let me know when you and dh are free to catch up some other time' is both polite and saying no to the daughter without drama and if they get offended that's their problem

It's surely better than just downgrading your friends to people who you are polite to but won't have dinners with . OP doesn't have to message her friends to say I don't particularly like or know your daughter, so it's a no.' or forcing yourself to have the company of a stranger when you're in need of some support

They clearly don’t go out much if they think this is ok to invite DD

we can rearrange for when your DD isn’t staying with you

that should be clear and to the point

I do think she needs to tread carefully, because these people clearly don't have an understanding of why it's not ok to just assume their dd tags along to everything, and are quite likely to be at least a bit offended if confronted by their lack of tact.

TBH I am such an introvert I would find it just as difficult as the OP has and would have them downgraded to 'people I'm polite to but don't do dinners with' by now

From the OPs second post " I feel awkward in front of the DD as she’s a stranger and I am still at the stage where I get very emotional talking about it. on reflection if I get upset though so what. I think the request just put me on the back foot as wasn’t expecting it. There’s been a few comments about how we’ve dined with the DD previously but that wasn’t our choice - she was there when we arrived to our friends home."

OP didn't know the DD was going to be there but she wasn't going to storm out of a friend's house because their DD was there, that would be bizarre.
If I go over to a friend's house I would expect to see their relatives there potentially, but I wouldn't then assume they would tag along to a dinner at my house. I don't think OP needs to tread carefully she just needs to say no politely to let them know she is happy to rearrange for a time when friends aren't hosting DD

How old are you that your parents are still bringing you up?

What???

"Childfree" isn't really relevant when the daughter in question is FORTY is it??

My parents have friends like this. Never had a family and get annoyed when people other than my parents are around. I have never tagged along to one of their lunch dates in their house though, but they make it clear they only want my parents on their own in their house. Their Attitude is perhaps caused by selfishness, not quite fully understanding what bringing up a family entails and that families can't just be ditched to accommodate childfree couples.

"The last couple of times we’ve hung out we went over to their house both occasions and their DD was there and joined us (for the whole evening not just the meal part)
For context, their DD is in her forties and has her own place but often visits her parents on the weekends." From the OP

It's not like they dropped in for 5 mins and the daughter happened to be there. I imagine the couple think that since their dd is there a lot and has socialised with the OP before, it's fine to suggest she comes to dinner. I'm not agreeing that it's right - it's not something I would do - but in context it's not exactly unexpected. The woman is often there at weekends. The parents have been invited and perhaps think the OP should reasonably expect her to know that their daughter will be around.

They are probably composing an AIBU between themselves that goes "Should this woman have invited our DD when she knew she would just sit in our house alone otherwise?"

I think the OP should just file this under 'people can be a bit weird at times' and tread carefully, unless she thinks the couple are being insensitive to her needs, to which I'd say, they probably aren't thinking of her needs at all, they just don't want to leave their dd on her own and think the OP knows her better than the OP feels she does.

Sounds like there's maybe something going on with the dd. It's a bit strange for a grown adult to want to tag along with her parents friends.

I'd just reply and say shall we arrange something at a more convenient time.

No dramatising things, she has met the daughter a couple of times whilst she was at the friend's house, she is as OP describes a stranger. She hasn't been inviting the daughter out anywhere previously. They are not a trio, the friends are invited, the DD is just her friends DD. I know my friends family's pretty well, they would never assume they could invite over family members to my house.

If she let them bring DD, it does open things up, it would them be assumed OP is happy for DD to tag along to whatever. The friends may have other children, if they think OP loves spending time with their DD, maybe next time DS should tag along too as its unfair to exclude him and she loves DD clearly, so she'd probably love him too.

The DD is in her 40s, if the parents are so worried, they can stay at home with DD. If there's nothing to worry about they should accept OPs wishes that she only wants her friends at her house. Her friends and her friends DD are separate people and OP doesn't seem them as a packaged deal for friendship and this should be respected

That is the most spot on reply 👏

Except the daughter's been around at previous dinners, so they might have assumed the OP sees them as a trio. No need to dramatise things with talk of the whole extended family

If the OP isn't in a friendship where she can say politely to friends that they can't just invite random family members to her house when she needs her own support without the friends cutting ties, then it's the friends who have problems not OP.
The friends can be there for whoever they want, it doesn't mean OP bears that responsibility by extension. What if the friends wanted the invite all their children and extended family because OP has met them over the years, would OP just have to suck it up?

I think that is cheeky and to say 'daughter will be coming' rather than 'can my daughter come?' is really rude. It is hard enough to say no when a guest asks if they can bring someone else but to say you will be bringing someone or just turning up with someone without requested permission for is even harder to refuse. You could try saying, she wouldn't enjoy it or you don't have enough space/food but that could backfire and you'll lose of the friends.