He was breastfed with her maternal uncle five times – is she forbidden for him for marriage?

Praise be to Allah.

If this young man breastfed from the grandmother of the girl, who is the mother of her maternal uncle, and had five full breastfeedings within the first two years, then he is a son to her (the grandmother) through breastfeeding, and he is a brother to the girl’s maternal uncle through breastfeeding, so he is a maternal uncle to the girl through breastfeeding and it is not permissible for him to marry her. 

But if he was breastfed with her maternal uncle from another woman, such as his own mother, then he is a brother to her maternal uncle through breastfeeding, but there is no relationship of mahram between him and the girl, and he may marry her.

And Allaah knows best.