I am looking for the marriages of four Hutchinsons, the siblings of my great great grandfather:

Norman b. 1846
Julia A b. 1853
Alfred R b. 1855
Emma D b. 1857

All born near Sigourney and the children of George and Elizabeth (Betsey) Hutchinson.

George and his family seem to (with the exception of one son George whose marriage I did find in iowa) seem to disappear from the face of the earth after 1860. They are on the Sigourney Keokuk 1855 and 1860 census as a family, and after that I can find none of them on a Iowa or national search. There are indeed other Normans and Julias and Alfreds, but none with the requisite data to match them.

Can anyone recommend a good source for this kind of problem? I am a bit of an amateur researcher, but a careful one and know both not to carelessly connect, but also that records of which I know nothing can actually be out there.

Thank you,

Neil