Hi, Rhonda. You don't need descendants to confirm your ancestral relations through DNA. What you need are siblings (which you have), or much better, cousins. You and a first cousin would share the same grandparents, so the right size match would confirm that one of your grandparents is a grandparent (but you don't know which one). But you do know which of your parents was a child of those grandparents, so you could mark that parent as confirmed.
If you have second cousins, they would share one set of great-grandparents, and would confirm whichever grandparent was a sibling of your second cousin's grandparent.