Can he marry a girl whose maternal uncle was breastfed with his oldest brother?
Question

                There is a young man who wants to propose to a girl. He found out that his oldest brother through his father was breastfed with the maternal uncle of the girl. Is he also regarded as a brother (to that uncle) which would mean that the girl is regarded as his sister’s daughter? Is it permissible for him to propose to her or not?.
Praise be to Allah.
    It is permissible for this young man to propose to the girl 
    mentioned, because there is no impediment to doing so. The fact that his 
    brother was breastfed with the girl’s maternal uncle does not have any 
    ramifications, not even with her sisters if there are any. The prohibition 
    affects the one who was breastfed (which in this case is his brother) and 
    anyone else who was breastfed by the same woman. 

    The young man mentioned here is not one of these people. 

    With regard to the older brother, if he was breastfed by the 
    grandmother of the girl, then he is a maternal uncle to her through 
    breastfeeding. 

    And Allah knows best.