I am looking to clarify some ancestor information on Derk Dokter, born 21 April 1839 in Drenthe, Netherlands and died about 1922 in Muskegon, Michigan, USA. He married Aaltje (Alice) Roossien in May 1867 in Drenthe, and their children appear to have been born in Groningen. They had ten children, and as of 1900, five were surviving and all living in Michigan, USA. The problem I am running into is that I believe that the information I am finding on parentage for both Derk and Aaltje refers to Dokters in another part of the Netherlands that are not related to this particular family. I worry that I am mixing the families up. I have original source info for Derk and Aaltje, so I am confident about the basics of their information, but I only have secondary sources for their parentages. Can anyone help? Thank you.