Hi Samyuktha,
I know that doing a BMT is not an easy decision, and this is why Cure Thalassemia has created its website and gives free advice, both remotely and face to face.
I confirm you that the sooner the better, if possibile no more than 5-8 years old, becuase after that age the results are less positive, since the patient is nor more class 1 and becomes class 2
A thal carrier can be an excellent donor.
You have written "his cord blood be used for BMT of my daughter?"
Please notice that Dr. Sodani and Prof. Lucarelli (the most experienced doctors in the world about BMT for thalassemia, both involved in Cure Thalassemia) always prefer to use the bone marrow of the donor and not the cord blood, because there are better results and the risk is lower. The only expeption is if they don't have access to the donor, but there is the cord blood of him.
As Andy said, I suggest to have the free advice on BMT of Dr. Sodani:
http://www.curethalassemia.org/free-advice-on-bmt/and you can also meet him in person in Bangalore for free:
http://www.curethalassemia.org/services/meet-dr-sodani-in-person/If you have any other question, please ask.