My adoptive parents died recently and their biological son, my “brother”, who always resented me, and I are heirs. He is threatening to get the adoption order cancelled to cut me out of their inheritance. Is this possible or likely?

No! A family member –such as a biological child – has no legal standing to apply to cancel an adoption order between adoptive parents who have passed away  and the adoptee,the  non-biological sibling. Furthermore ,Israeli courts will not encourage such action when it is clear that the driving force behind it is a desire to deprive the adoptee of his inheritance rights. These points were made clear by Beersheva Family Court in 2017 which threw out such an application, and ordered substantial costs against the adult biological child, who had applied to cancel the adoption order relating to his non-biological brother within the context of an inheritance battle.