How do i get custody of my 16,13, & 9 year old nephews?

take it to court. call child services and have them investigate for abuse. Then if they take them away, ask if you can get custody. Almost all of the time they will give the children to family instead of putting them in foster care (unless you are seen as "unfit" or you are as bad as their mother). Good Luck and Thank you for doing the right thing!