How do you say "justin became one of 2 lead vocalists" in french

Just say ''Justin est devenu l'un des deux chanteurs'' and that would be your answer.

Bonjour, 

On traduit par "Justin devint un des 2 chanteurs principaux (ou frontmen)". 

Translation: hello! i'm marianne and i'm from montpellier, france. here is a picture of my family. in the photo, they are my grandparents, my uncles and aunts, and my parents. they are in the garden at my grandparents' house.this is my grandmother's birthday on november 8 and we are all at home for this occasion. my grandmother is seventy-nine! my grandfather is older. he is eighty years old! my uncles and aunts are very nice and interesting. they are with my parents and my grandparents in the picture. i take the picture and that's why i'm not in the picture. i'm happy with my grandparents because my cousins ​​are there when we're here and we talk and play together. it's fun to be with the family.my family is very good and active. i love my family! how is your family? do you have cousins ​​and grandparents? where are they? now draw your illustration based on this short story