It is very important to have the shrink in the loop before starting. Everything is about comfort zones. I broke under the dysphoria and told them before telling my wife and that put them in a bad position... the kids are 18-24 years old. It was hardest with the wife and that was done with the shrink breaking me down to come out as I had hidden it all for 25 years, successfully.
Everyone is different, I found what each is comfortable with handling and scaled my stuff back to their comfort levels, expect with one respect and that is my nails and shaving. I cannot cut my nails without discomfort, and forget body hair. But showing bare hair, or painting nails, those I can either hide or not do around them.
2 kids have seen me full transition, the wife sees partial transition all the time, and the other kid sees as little as possible. It is just the way it has to be.
I am extremely lucky. I was able to salvage everything except sex. That I and my wife lost to the dysphoria, but that is the only thing we lost, except losing dishonesty.
Get the best shrink you can.
Also, unselfish Christian values helped. Not the judgemental part, we are often misunderstood, but the unconditional love part, and the acceptance and refusing to be selfish part.
And all that is good and that strengthens our relationships accross the board, we make sure we nurture.
But I get aggravated if my privacy gets unintentionally invaded and the kid that can't handle it gets mad. The bedroom is off limits to her withoiut knocking for good reason, and if she saw me in lingerie wigged up or fully transition wigged up, or God forbid nude with my preop half full transitioned body, it would result in massive trouble. My wife accidently caught me from the top up in a cami and it messed her up for a short time, she just can't handle it. I can cover up I know my core physical needs are female, but a girl in jeans and a sweatshirt is still a girl. So I am cool with it.
Shrink, advice, and a lot of courage and understanding will be needed. I softened them up with the Friends epi's with Chandlers dad in them, she is TS or TV they don't say, but I believe full TS on the series.
Just to catch their reactions. Actually they showed it to me first, clueless, before I broke. Then we revisited it.
Good luck. It is wonderful to live in truth but it can come with a cost.
Time heals. My wife had a vision of Christ to stop fearing and keep me and that also made an enormous difference, but she considered leaving me first and then decided to stick it out. And we are very close. It is hard if they percieve girl on girl there are issues they may not be able to overcome. It is hard for the kids because when we were normal men to be percieved, we bacame their rocks, their stability, and a huge change like that is hard for them to process, particularly if they have anxiety issues.
Take it slow... get professional help doing it first... I did it wrong but then did it right later with my wife. It took me 9 months to admit that I was on hormones. It took 2 months of therapy to admit I cross dressed.
A lot of my explanation has been medically based as well. My incompatibility with testosterone and the fact that I have estrogen receptors in my head, the DES exposure for me in utero which transitions your central nervous system before birth, permanently... these are things that have helped preserve that which I hold dear.
Hope something in here helped.
Not easy.