Is it permissible for me to marry the daughter of my paternal uncle, who was nursed by my mother from my grandmother (my mother's mother), knowing that I also nursed with my young maternal uncle from my grandmother?

Fosterage establishes prohibitions (on marriage) just as consanguinity does, based on the Prophet's (peace be upon him) saying: "What is prohibited by lineage is prohibited by fosterage." Therefore, if you and your paternal uncle were suckled by your grandmother, you become foster brothers. Consequently, it is not permissible for you to marry your paternal uncle's daughter, as she is considered your foster niece. It is a condition for fosterage to establish prohibition that there be five full, satisfying sucklings.