Her brother was breastfed by the wife of her maternal uncle; are her uncle’s children mahrams for her?
Question

                My brother who is two years younger than me was breastfed by the wife of my maternal uncle, along with her own son. Is it permissible for me to uncover in front of this uncle’s sons, i.e., to not wear hijab in front of them? What is the ruling on my sisters who are younger than the brother who was breastfed by the wife of my maternal uncle?.
Praise be to Allah.
      If breastfeeding is proven to have taken place, and he was 
      breastfed fully five or more times within the first two years of life, 
      then your brother is a son to your maternal uncle through breastfeeding, 
      and he is a son of your uncle’s wife who breastfed him. Their children are 
      his brothers, and your maternal uncle’s brothers are his paternal uncles 
      and his sisters are his paternal aunts. The brothers of the woman who 
      breastfed him are his maternal uncles and her sisters are his maternal 
      aunts, because the Prophet  (peace and blessings of Allaah be upon 
      him) said: “What becomes mahram (forbidden for marriage) through 
      breastfeeding is that which become mahram through blood ties.” Saheeh – 
      agreed upon. 

    But you have no connection with the breastfeeding mentioned, 
    and it is not permissible for you or your sisters to uncover in front of the 
    sons of your maternal uncle on the grounds that your brother was breastfed 
    by the wife of your maternal uncle, because they are not mahrams for you.  

    May Allaah help us all to understand His religion and to 
    adhere to it.