Ohhh Sollan,
Hard call at the best of times. Regrettably you know your daughter better than all of us put together. Particularly she being 'religious'. My experience has shown me, a lot of biblical Christians are only too happy to take any quote from the 'good book' out of context and hurl it at you, to please themselves. I don't wish to be offensive here, that is just my own personal experience; which includes being asked to leave two churches because of my gender identity. If I offend anyone, please accept my sincere apologies.
Meanwhile, back to your daughter. I'm in a similar boat. As to the logistics on how, when, where and why I and what I divulge to siblings is very much a case by case situation.
I wouldn't be too concerned about the application of the 5th commandment. As regrettably, yet again they have never been relevent to secular society and are a fading tenement within institutional religion.
The only guide I can see as being some vague form of assistance here is how you nurtured your daughter. If you identified yourself as the man when you raised your daughter, you would have nurtured her in that context and would know the best way to approach her based on that nurturing. If on the other hand you identified yourself as woman at that time, the nurturing would have been more consistant with mother/daughter relationship, to which I'm sadly lacking.
Whichever way you do it, there will be shock, anger, denial, grieving, pain and disassociation in some form or another. In much the same way I see my dilemma with my wife. I can either start dialogue and go through all those feeling mentioned above; or leap out of hospital one day and say "Ta-da" Guess what I've got? It's just like yours! And wait for the response; which may be the same as above, on a greater magnitude.
You know your daughter, you know your journey. You will know what is right. Sorry I couldn't have been more helpful. Just know you are loved by all of us here.
Be safe, well and happy
Lotsa luv
Catherine