Marrying a paternal cousin

Q: There are two brothers; the elder brother is called Shari` ibn Muhammad and the younger is called Nasir ibn Muhammad. Shari` died and left behind three daughters and a son. Nasir married his brother's wife who gave birth to two sons and two daughters. Nasir has children born to another wife. Is it permissible for Nasir's sons, who are born to a mother other than his brother's wife, to marry the daughters of their uncle Shari`?

A: It is permissible for Nasir's sons, who are born to a mother other than his brother's wife, to marry the daughters of their uncle Shari` ibn Muhammad. The fact that their father is married to the wife of their late uncle does not render the marriage invalid. However, the marriage will be Batil (null and void) if, for example, the sons and daughters are related to each other by means of breastfeeding that affects marriageability. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.