Is it permissible for the two brothers to marry the daughters of their maternal aunt, who breastfed them and their brother?

If the maternal aunt, whose daughters you and your brother wish to marry, breastfed both of you, then it is not permissible to marry her daughters. This is because they would be your sisters through rada'a (nursing), according to the Prophet, peace and blessings be upon him, who said: "What is forbidden by lineage is also forbidden by rada'a." And according to the Almighty's saying: "Forbidden to you for marriage are your mothers, your daughters, your sisters, your father’s sisters, your mother’s sisters, your brother’s daughters, your sister’s daughters."