A woman marrying her brother's paternal cousin who is his maternal half brother
Q: My full paternal uncle married my mother after (Part No. 18; Page No. 342) my father had passed away and they had a son.
However, this uncle of mine had a daughter from a previous marriage. We all used to live together. Is it permissible for me to marry my cousin i.e. my uncle's daughter from his first wife?
It is noteworthy that my half brother who is my cousin as well is at the same time a half brother to my cousin whom I want to marry but we are not milk brothers.
If the reality is exactly as you have mentioned, it will be permissible for you to marry your cousin who is the daughter of your uncle from his first wife. The fact that your uncle's son is your half brother and that the latter is the half brother of the girl whom you want to marry does not affect the permissibility mentioned above; your cousin whom you want to marry is still not a Mahram (unmarriageable relative) to you. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.