My grandfather has one brother; my grandfather has a son, and my grandfather's brother also has a son. I am the son of my grandfather's son. The brother of my grandfather has a grandson, and I want to marry his grandson's daughter. Could u tell me whether this is possible or not. Can I marry her?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.

Your grandfather's brother is your father's paternal uncle regardless of whether he is the full brother of your grandfather or the half-brother on the mother's side or father's side. In any case, in principle, it is lawful for you to marry the daughter of the grandson of your grandfather's brother as long as it is not proven that you and her have been breastfed by the same woman the kind of breastfeeding which Islamically establishes the prohibition of marriage. This should be five separate sessions of breastfeeding, in which the child eats his fill, according to the preponderant scholarly view.

Please, refer to fatwa 85868 about the categories of women to whom marriage is unlawful to the Muslim man.

Allaah knows best.