Looking for Luke Family from Nebraska

I am looking for information on my grandfather William LUKE, born in PA, 1864. I do not know where or who his parents were, only they were in PA. He married my grandmother Ida Groves from Iowa and they lived in NE, around the Chadron NE area. My father Elmer LUKE and my mother Rosetta Scott were married in NE and lived in Chadron, NE, before moving to Iowa. I have info on everyone except my grandfather, it is as if he just appeared.