Bob, I think your Myron Fifield is the sister of one of my brick walls, Anna May Fifield.
I have Myron in the 1870 Gratoit Co, MI census as being born in 1865 (calculated) and Anna in 1867 (also calculated).Anna is the GGGranmother of my wife.Anna and Myron are listed in two different households.
Anna lived with Thomas and Almira VANCE. Myron lived with Catherine and Jeremiah HARRINGTON.
No other FIFIELDs in that area in the census, and no information in the 1850 or 1860 census on the Fifields in Gratoit Co, though there are plenty in Ionia Co, Mi.
Do you think there is a connection, and do you have any more information on the Fifields?