Hola me llamo Tobie and I would be more than glad to help!So to comprehend let me walk you through every step of the way!
Su
Explanation:
Mi= me
mis=mine
su=hers/his
nustra=our
In English it would mean I am their cousin
Therefore Su would make more sense if you put any other word than Su It would be considered improper grammar in Spanish
Hope this helps!
-Tobie the dog <3
