Thanks for the info on my Texas relatives (Carl David Nelson b. 1864 Sweden). Carl David Nelson and Andrew Peter Nelson (according to their marriage records) have the same father but different mothers.
However, I am still looking for info on Nels M Monson, my great great grandfather. My great grandfather,Andrew Peter Nelson (born ~1856 Sweden,)was married in Algona, Kossuth County Iowa Mar 14 1890 to Christina Hansen. The marriage record says that Andrew Peter Nelson's parents are Nels M Monson and Johana Bengstron (both believed born in Sweden).
Is there any chance to discover more about Nels M Monson by looking for info on his marriage to Johana Bengstron?
I am quite sure that CD Nelson is AP Nelson's brother based on a verbal family history and the use of "Carl David" in AP's descendents. It may be that Nels M Monson was widowed and remarried. I don't know how else to explain the different "Mothers name" info for the two brothers.