Is a maternal male cousin, if he is older, considered a brother through suckling if the mother breastfed him three or four times? Is it permissible to marry the younger maternal male cousin who was breastfed by the mother twice, with unfilling sucklings, knowing that he proposed after learning about the suckling? And if the older brother is a brother through suckling, is it permissible for the younger brother to marry the sister of his brother through suckling (who is the younger maternal male cousin)?

Scholars have differed regarding the amount of suckling that causes prohibition (of marriage), and the most preponderant opinion is that prohibition does not occur except with five known sucklings, due to what was authentically reported from Aisha (may Allah be pleased with her) that this was among what was revealed in the Qur'an. It is stipulated that the suckling must occur within the first two years (of the child's life). As for defining a single suckling, reference is made to custom: if the child suckles and then stops suckling voluntarily, and then returns, each instance is considered a separate suckling.

Accordingly, if your maternal aunt's two sons suckled from your mother less than five satisfying sucklings, they are not considered your brothers through suckling according to the preponderant opinion. However, it is recommended to abstain from marrying a maternal aunt's son as an act of piety.

As for the siblings of a brother through suckling (male or female), they are not considered siblings to you or to your brothers and sisters, because they did not share in suckling from your mother.