Genealogy assistance

Hello ,

My Grandfather and Grandmother came to Pennsylvania , USA about 1882-1883. His name was Leopold or Lucas Kosisher (my maiden name)
He was a young boy at that time, age unknown?
My great grandmother was Susanna Mueller or something to that effect because the death certificate was blurred. She married Lucas or Leopold (Kosisher) and they had my grandfather, Leopold and two daughters, Mary, and ,Agnes and that is all I know for sure.
I have no idea where or how the name Kosisher originated? It could have been misspelled many times over because of interpretation and their ethnic background?
Thank You for your help in this matter. Sincerely,
                                                                                       Jean

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