First, I am very sorry to hear of another women enduring this painful process.
I was in your situation last May, when I had a late term miscarriage of our son. We had already told my 4 yo daughter, and I was already showing, so it was clearly a difficult time-- as this is for you!!
We handled it, by bringing our faith into the picture. That God had decided that this baby was special, and he chose it to be with him. We spoke about it very openly, and honostly (within limits). I told her that it was very sad and painful for both mommy & daddy, and that it is ok to cry about such things. We also talked about how that baby will always be our guardian angel, looking over us. We also planted a beautiful rose bush, where we can go whenever we need to talk about it, or to remind us of this time. I made a scrapbook of ultrasounds, papers, cards, etc. Which we also look at occasionally.
Now, I am pregnant again, and it has brought up questions again- However, she doesn't seem upset or scared about this pregnancy. Not that I am not- but we still talk about it and it is VERY endearing how much she cares about the babies! and me! We also include both babies in our nightly prayers.
I hope that this is helpful to you-- and try to remember that how you handle yourself, is a guide to her. Showing your emotions can help her know that is ok to grieve. Letting her ask questions and talk about it without feeling weird is also a healing mechanism. Time will pass for all of you-- and I wish you peaceful healing!