I don't know if there is a connection here or not but it seems very probable. My gr-gr-gr grandmother was Mary Jane Alder, born in Mahaska county Iowa. On a slip of paper that was in a family bible in the possesion of my grandmother was a list of siblings of Mary. Isaac was a name listed. All I have is a name but I will check some of my census copies from Mahaska to see if I can determine a date or if it lists a Isaac on it. Feel free to email me at firstname.lastname@example.org.