What is the degree of kinship between the sons of maternal aunts who were suckled by the two maternal aunts – are they considered maternal uncles to the sons of the other maternal aunts or not?

If your two maternal aunts' sons breastfed with two of your maternal aunts from your grandmother, then they become maternal uncles through rada'a (nursing) to you and to all your maternal aunts' daughters. If they breastfed from someone other than your grandmother, then each of them becomes a brother through rada'a to the maternal aunt with whom he breastfed, and a maternal uncle only to her children, unless the milk from which they suckled necessitates mahramiyya (prohibition of marriage) from another aspect. Five fulfilling breastfeedings are required for prohibition.