I finally managed to compose a letter.
"Dear Jorge's Parents,
There is no way to thank you enough for the gift that Jorge gave our Babygirl. She was on dialysis for a long time, hooked to a machine all night, every night. Since she received Jorge's kidney, she has been able to sleep - no machine, and no pain.
Your description of Jorge, 'a boy very beloved, and with a big heart,' could be a description of Babygirl. I think they are a match in every way.
Babygirl is in 6th grade. Last week she was able to attend school for all 5 days for the first time all year.
Thank you is not enough.
PS We would be very happy to hear more about Jorge"
I included two pictures of her, one recent, and one when she was younger.
I hope they write back. It took about five weeks for us to get the letter they wrote, so it may take quite a while.