I have a mystery on my hands, hopefully, one of you can help me.

My great grandfather, was Isaac Bear, b. 1810/14 PA; he married a Susanna/Susannah ?; I don't know, if Susanna was his first or second wife. Over the years, they had 12 children between the 2 of them. I found on one census a Robert A. Trotter and a Thaddeus Trotter living with the family. Was these 2, Susanna's children, or were they kin of the family. Was Susanna a Trotter, or had she married a Trotter. Susanna was born in PA abt 1810/1814.

This family lived in Johnson County Iowa by the 1850 and 1860 census. I then found Robert on the 1880 Kansas census. There were several Trotters living in Johnson County the same time period. I believe possibly that Thaddeus changed his name to Bear and he was found on the 1880 Iowa census.

Thank you for any help or suggestions you may be able to provide.