Adult daughter dating trans-identified male, struggling to navigate family concerns

It's not really any of your business what genitals your daughter's partner has.

If you want to end up NC with her then carry on.

If you actually want a relationship with your daughter then suck it up and call him "he", it's not going to ruin your life unless you choose for it too.

I have a right to consent - give permission for something to happen. My daughter has changed, dramatically actually

Your daughter is an ADULT though. Capable of making her own decisions on who she does or doesn't date.
Just like her partner is presumably an adult too and makes their own choices.

I will not perform because someone else tells me to because if I don’t do things their way they will feel offended. Be offended. Then consider why you are offended
I mean, I literally said it's your right to hold your beliefs and use what pronouns you like. I'm not offended in the slightest, so not sure why you think I am when nothing I've said has indicated that?
Do and say what you like. I've never said otherwise.
You seem desperate to find offence yourself or you're deliberately misunderstanding or not reading my posts, who knows.

I am navigating things to ensure communication and contact with my daughter are maintained
If you refuse to use preferred pronouns (which is your right) and you think of your adult dd's partner as mentally ill, genuinely interested in how you're navigating communication and contact? Hope it's working out for you. As it all sounds so hostile.

The OP has said repeatedly she's happy to do that, but her DD is demanding she refer to her partner as 'he'. That's a step beyond being civil and accepting; it's in dogma/manipulation/coercive control territory.

As Sylvanmoon says, just find common ground with your adult child's partner, like you would hopefully do with anyone they were in a relationship with.
You can hold whatever opinion you like on them privately, just be civil and accepting when you see them otherwise it might push them further together and you further away.

Jesus can we stop with all the mentally ill and trauma stuff. My child is autistic, I believe this is why they are trans. Happy childhood and still a happy person. Just autistic and trans.

@BlueLegume here's some evidence about the desistance rate for girls:

As a fellow sex-realist who would find this situation deeply troubling, I think, as others have suggested that you need to find a way to navigate it for now. We know that there is a high rate of desistence, especially in girls, so perhaps you may be a catalyst for this young woman to reconsider her decision. I wouldn't be focused right now on the fact that there is a degree of mental illness that must dictate such drastic action. I would focus on not playing along with the fiction, while at the same time showing your daughter that you love her. And similarly, you can try to find something to value in the woman she's "in love" with. Perhaps, rather than write her off as mentally ill, feel sorry that whatever personal trauma she has experienced must be so painful that it has led this young woman to remove her breasts and whatever other bodily modification she's undertaken. I don't think this will be an easy journey for you, but it may in some way be able to heal another person.

Ok

You started a thread about how to navigate this relationship, your posts are mostly attempting to educate people and sharing links to reinforce your beliefs but you don’t seem to be interested in the issue you started with? Which was around your relationship with your daughter.
I actually feel the same way as you about some of this and I don’t need educating.

you are educating people on a board set up for people who are interested in this topic and most of them already know all of this anyway so why do you keep attempting to enlighten people? (In quite a patronising way)
You don’t seem interested in talking about how to make it work with your daughter, just sharing all your knowledge about the trans issues

Needless bodily mutilation to join a cult is (at least) a centuries old custom.

As for patronising - it doesn’t get much more patronising than your comment about ‘back to the mutilation part of your loop’
Are you confusing me with someone else? I've never used the word patronising. Somebody else did upthread, and said you were - not me though.

For those with different opinions to the majority posters on this board, what is it you actually disagree with? We keep asking but none of you answer. If this isn’t the thread for it, you can be the first to answer on the attached thread which is specific to this question.

https://www.mumsnet.com/talk/womens_rights/5402604-5402604-jkr-asking-similar-questions-to-what-i-have-been-asking-for-years-on-here?utm_campaign=thread&utm_medium=app_share

am open to different opinions with a view to someone bringing some evidence to me that will persuade me that people can change sex. As yet no one has done this
That's not what the thread's about though?
Maybe that's why. Thought you just wanted advice about your adult daughter? Although I see we're back to the "mutilation" part of your loop.
Edited to say it's clear you don't want advice at all, just a chance for another cult mutilation social contagion" "debate".

For the young it's a social contagion just like eating disorders & self-harm which also are more common in adolescent girls. Evidence for this is that before the madness of the last 10-15 years lying to children that they could change sex there were no kids who thought that they were "trans".

Needless body mutilation is a high price to pay to join a cult.