Do those under sponsorship have inviolability due to breastfeeding, based on Fatwa No. 94013?

The possibility that the fostered children are milk-siblings and mahrams is unlikely, because those who adopted you were infertile, and the age difference between you, and the age of the other adopted child (two years old) at the time he was taken from the orphanage, all make that remote. The default is the absence of mahramiyyah, and one does not deviate from this unless lawful suckling is proven.