Transfusion interval is decreasing

Dear all,
My daughter is 9 years old. Earlier she needed transfusion every 4 weeks but since a year the requirement is decreased n now she needs every 15 n sometimes every 10 days. Her ferritin is around 4000.
Pls advise. Thanks.

Pls anyone revert/ advice. Thanx...

Has she been checked to see if she has had an antibody reaction to the transfusions? It may be that the blood needs to be better matched.