I’m worried DHs daughter isn’t handling us having a child well

Agree this is the most likely, she is an adult but her dad having a baby at 50 probably wasnt a possibility she had considered before.

You sound lovely and that you are doing everything you can. Keep talking to her, maybe you could give her a list of names
that you like and she could veto what she didn’t like (that would be very generous of you). Show her she is part of your family and important. It must be very hard for her knowing than her only parent and her sibling is going to have a family unit that she isn’t in and has never had. Patience, love, time and understanding and I’m sure she’ll come round and come to love her little sister.

I think all the posters who have referenced the fact that your child is potentially going to grow up having her dad and a mum have hit the nail on the head

She will be feeling so many confused, mixed emotions around this, some that she probably can't even express.
It will be bringing up all her insecurities around her own childhood, her relationship with her mum, fears about "losing" her dad, feeling so far away from you all
Poor thing, it's a lot to take on & I think the physical distance compounds it all.

It's lovely that you are recognising this and are concerned. I think you should advise your husband to have a talk with her to encourage her to open up. He might even suggest (and pay for?) some counselling if she would be open to it.
But I think in the first place, her dad acknowledging that he understands how huge this is for her and showing that he cares & wants to help is the first step.

Your empathy (and understanding of human nature) know no bounds 🤣

You sound lovely and given her age I doubt it's about wanting a baby herself.

When I had a child I almost watched what could have been, if you know what I mean. I saw with fresh eyes how I would never do X with my child and it felt painful in a different way. For example, i remember one parent regularly cancelling a visit at the last minute and being sad, but when I became a mum and had a child that age myself,my heart shattered 10x harder imagining DC in that pain.

What I'm getting at here is that she may be very sad throughout the life of this child. Right now, your DC has a stable family; she didn't. This child has a full time dad in the same country; she doesn't. She will basically be witnessing first hand how her life could have been and that will bring a lot of different pain at different points. I commend your compassion.

Perhaps not might be easier for her for her dad to visit her on her home turf?

She's an adult but emotionally dealing with your pregnancy like she was a small child. It's not unusual for adult children in second marriages to react badly to the news their parent is expecting a new child. Adult or not, they think the baby will take love, affection (and money) away from the parent that was "theirs".

You need to give her time to deal with her emotions, because she's reacting to primal fears instead of dealing with her feelings as a mature adult.

Hopefully, she'll be able to move on and embrace your child as a sibling, loving and supporting them. Unfortunately, it's not guaranteed she'll do so.

Why is that ridiculous? If I got a new step dad who I doted on, lived with, loved and called Daddy, it would have upset my dad just as much. He wouldn't be thinking how wonderful it was for me to have an extra father in my life.

At 25 she probably is looking forward to starting her own family. And you have got in there first. She is understandably sad and lonely.

How ridiculous

My exH who is 50 now has a 1 year old and a newborn with his new wife.

our children together are 24 (I had twins).

his new family has very clearly replaced his adult children and he no longer has any time at all for them (not that he ever had much).

They are sad. They’d always hoped he would engage with them and he’s chosen to replace them instead.

he’s tried to get them to babysit their new half brothers and all sorts of things.

Hell, you're not even 'geriatric pregnancy' age in your early 30s. Grandparents in 30s is more Daily Mail fodder!

What did you expect? It would really upset me as well. For 20 years she has been his only child and now he is having another one. She will feel like she has been pushed out. My father was with someone else when I was in my early 20s. I would not have been thinking kind thoughts if he announced he was having a baby. I would have thought he was too old and that it was a betrayal of our relationship.

I think this is your answer. She had a traumatic childhood and she's about to watch her dad start again with a baby that (hopefully) will have the loving and stable childhood she should have had.

Added to this, her dad is naturally going to giving his new child a lot more love and attention in the here and now. I think it would be difficult not to feel replaced or pushed out in her shoes (I didn't have a traumatic childhood but would have hated either of my parents to start a new family... I'd have sucked it up and smiled but I would have hated it.).

Could the angst about baby names stem from her worrying that he won't care about future grandchildren as much if he's starting parenting again?

She's afraid she's going to lose the special love that a father has for his only daughter.

Only time and reassurance from her father will help this one, but she is also right to an extent, the new baby is likely to enthrall him. I don't feel this one is going to get easier any time soon, but it isn't your problem, it's hers and she needs counselling for it, sadly.

I mean she's in her 20s
Not a a young child or a teenager
When do people grow up?
I fear people who are still like this in their 20s never do.

Her family is changing drastically and she has had no say in it.

Yes, she’s an adult, but family relationships are still absolutely fundamental to anyone’s identity. And it seems that she’s very apprehensive: her family is no longer one in which she knows her place and her role.

You and your husband should be compassionate about this.

Although I imagine the MN warriors will say she just needs to grow up!

Both things are true, I've 2 friends from childhood who had their eldest as teens and now in our 40s are in new relationships and have had babies this year while their eldest has made them grandparents recently too.

I think @HellonHeels has it spot on. It's about what your baby will have that she has not - a mothering relationship. She is probably upset and embarrassed about the feelings this is bringing up and maybe is actually being protective of all of you by not wanting to be potentially upset or affected being there when you have a newborn. It's could be very confusing for her.

I think she’s shocked and reacting to a situation she didn’t anticipate - she didn’t think this was on the cards. DH needs to keep talking to her, so do you if you have a good relationship, and keep lines of communication open.

She feels she's being replaced. She's grown up, and now he's going to have a new little girl to dote on. She may not be able to articulate it, but I'd put money on it being this.

It sounds like she has a lot of issues to deal with surrounding abandonment, some of it could of course be jealousy if she has that weird dynamic some women continue into adulthood of being a "daddy's girl". I lived with a few women in my early 20s who had this sort of relationship with their dad's, as 1 of 3 and not the only/youngest girl I found it all a bit weird and nauseating as an adult.

I think it'd be quite infantile to ask her to be involved in naming your child, she's 25 not 5! Her issues aren't for you to deal with anyway, I'd be reluctant to dance around her like you are introducing a new baby to a toddler. She lives in a different country, I'd leave it up to her dad to deal with any weird behaviour and focus on your baby.

My Dad became a full time step parent to two very young children when I was in my early 20s and he was 50ish and he did a much better job looking after them than he ever did with me. I guess the benefits of being older and wiser, having more time and money but it also seemed that he wanted to be doing it whereas when I was young he did not enjoy parenting at all.

I suspect this situation has raised a lot of difficult memories and thoughts from DSDs childhood and she's deeply processing what happened to her. It will likely change their relationship forever, but thats not necessarily bad, just a shift in her viewpoint.

As a 25 yr old I'd have been horrified if one of my parents essentially started again with a new baby. 50 is old to have a new baby. He will be retirement age before she finishes at school! She probably thought he was finished having kids, this will be a big shock.

She isn't going to have a sibling relationship with this child, she's old enough to be her mother which creates an odd intergenerational dynamic, if she has her own children in the next 5 yrs or so they'll have a 5 year old "auntie" which is uncomfortable for a lot of people.

the overthinking is real - im a phd in these subjects and ended up in psychosis from anxiety

Why is her mum not around? And how long has that been the situation? That could be having an effect on her - she knows she will see her sibling have a mum. And she will see you, her dad and baby as a unit and maybe she worries where she will fit in. Also, despite being in her 20’s she may not be able to articulate why she is upset or perhaps she doesn’t even know why.
I would say keep communicating. Maybe dad (or you) write her a letter? Whatever your normal communication is when she is back at her home - don’t let that stop.

eta somehow I missed a whole bunch of posts! Can see the mother issue has been raised. I bet you that is the root of it.