My formerly estranged brother has transitioned and wants back in mine and my mother’s lives.

I don't see that you need any conversation with your brother. Your Mum wants a relationship with her son, and is willing to tolerate his beliefs, in order to maintain a relationship. It doesn't mean you have to do the same.

You don't want a relationship with your brother, you just need to be able to tolerate him at family gatherings. That means being polite and civil. If being civil means referring to him by his new name, then is that any real hardship?! It's a name, nothing more and doesn't mean you agree or support his decision.

How old are your children? Old enough to know and remember you have a brother? With most young children, if you introduced your brother as 'Mary', then they're likely to just take the name and him at face value. If they're a lot older, then yes, you may need to explain your brother is trans, and what that means.

You've managed for years without him and presumably as your DC are young he's never been in their lives.

He has deliberately 'forgotten' his past behaviour and probably wants contact now so that you can pander to his bravery and lovely womanliness and validate his delusion. You don't want him back in your life so trust your instinct and tell your mother you appreciate her not wanting to be cut off (the very epitome of trans gaslighting btw) but that you will not perpetuate his fantasy, nor do you want your DC to be brought into this world of batshit, and therefore will remain NC.

If he's not spoken to you about it I think the discussion is a moot point given you only know from your Mum and she wants to see him.

Oh and if your mum or he push for a nice family Christmas, I'd have already made plans. It's a stressful enough time as it is and you'd have a job keeping the kids away from that one.

He’s contacted you to say he wants to be close? Or your mum has told you that?

I personally would move heaven and earth to make sure he was kept well away from my kids. They do not need this from someone they do not even know.

@AralVorkosigan has it bang on

I think you should go with detached indifference. Don’t discuss anything with him, don’t use his new name, just say the least amount possible and be ‘busy’ if he asks you to do something.

I think I would start by supporting your mum. You can do that by talking to and listening to her.

I don’t think you need to be proactive, on contact with you the ball is in their court. You’d expect in any circumstances some admission of past failings or failing that some acknowledgment of wanting a fresh start. If you don’t get either of those things then I wouldn’t hold out hope they’ve changed.

Any reconciliation is always a slow process with work on each side. And often stop-start. I don’t think you need to set out your position on trans stuff, it’s too early.

We have a newly transed niece, complete with a shiny new name and pronouns.

Given her other issues the fact that she has now proclaimed herself a “man” was fairly predictable.

The entire family thinks it’s offensive nonsense, but we are all keeping our mouths shut, for the benefit of the girl’s mother.

So no one has said what they think, or in fact addressed it at all. We politely use the new name if we can’t avoid it and have so far successfully avoided using male pronouns.

The unfortunate side effect is that no one directs much conversation to the young woman concerned or asks much about her anymore for fear of accidentally setting off a familial nuclear bomb.

If your brother isn’t a nice person, I would advise quietly supporting your Mum and otherwise saying as little as possible and staying well away.

Just keep him as you have previously - estranged.

The best you can do for your mum is listen patiently to her as she discusses what is going on.

Your example of not engaging might actually show her that she too can step back if she wants to.

But it could turn into a dramatic showdown, you haven't seen him in years, now he's living as a woman and the first thing you want to do is to clarify what you think about his situation? Why would he respect that? I think not saying anything in this case would be a lot better.

A previous poster mentioned "drama and squawking". It sounded a bit odd.

Alcove is right.

Tell your mother you're happy for her to have a relationship with him, you won't be talking about him to her, you'll be polite when you see him (no need for names or pronouns if you're in the same room speaking to him), and you will be choosing when to visit if he is there (possibly less than usual) and the kids may or may not be available (they won't).

Hmm. Ok. Well I would start here - you have a callous sibling you dislike to the extent you went no contact. So what has changed? Unless sibling is claiming their gender identity was the reason they were an awful person’s md now they are their true selves they are delightful, the transition is pretty much a red herring?

Sibling can want what they want but that doesn’t mean you have to agree to contact. That sounds by far the easiest solution.

Try the stately homes threads, we are all very supportive as NC or LC with our families or only certain members.

in this case support your mum but don’t have anything to do with the estranged person. Think about yourself and your kids.

Your brother has been estranged from you and mum and wants to have a relationship with you all but you don’t like him as he’s awful.
He is transgender now and you want to support your mum.
You can make it clear you do not want a relationship with him, you do not want him in your children’s lives.
You can’t support your mum with accepting he is transgender because you don’t believe in it.
Your only option is to stay away when he goes round because your mum wants to have a relationship with him and let her accept him being transgender by herself because it will break down if you are involved.

Hope you find a way, OP.

@RedToothBrush is the poster with brother experience IIRC. Hopefully she will see this thread.

So this is not somebody you want in your life, regardless of the trans stuff?

I’d be civil but distant - sort of like you would with an acquaintance that you don’t much like and don’t want to become friends with. Think of him as one of your mum’s faintly annoying friends from church (or bingo, or whatever it is she might do that doesn’t involve you!).

For the sake of your mum it’s good if you can avoid drama or actually cutting him off in a big row, but there’s no need for you to have him in your life or have your kids around him.

If challenged on him wanting more time with you, wanting to see your kids etc, I would just say that given the history between the two of you, you’re taking things slowly, and at the moment this is the amount of contact you’re happy with. Don’t make big pronouncements they can argue with, and leave it open that if he behaves well then in future the relationship may improve.

Never never get dragged into a conversation about the trans stuff, because if you do not completely toe the line he will likely get explosive and cause a huge row.

You can use his chosen name (I think people are allowed to choose their own names however much you don’t like their choice!) and avoid using any pronouns. If he notices you’re not using he/she, just say you don’t want to get it wrong so it’s easier to use his name.

If directly asked for your views on the trans stuff you can simply respond that you know it’s a controversial topic, it’s obviously important to him, and in the interests of family unity and building your relationship you don’t want to get into any big debates.

FWIW I have a sibling I don’t like, and tolerate occasionally in the interests of family harmony. If they came out as trans I’d roll my eyes, but it wouldn’t change anything about our existing relationship.

There won’t be any squawking if the Op doesn’t have a full and frank discussion about her thoughts and boundaries!