If you can find a regular blood donor who is closely matched for your son, you can set up direct donation. I know others in California who do this. The fewer donors for a patient, the better, as less risk of developing antibodies.
The families I know have the donor go 5-7 days before the child's transfusion, and the blood is processed specifically for the child.
I know a family where the mom and dad do direct donation for their child.
I also suggest you contact Eileen Scott at Cooley's Anemia Foundation.
Sometimes the hematology/oncology doctors are so used to "curing" cancer patients, that they can "push" BMT on thal patients - a condition in the U.S. that can managed in many cases. BMT is NOT being advocated by Cooley's Anemia Foundation, even when there is a perfect, silbing match.
I realize there are exceptions, such as people who have very difficult to match blood types.
Nicole