Re: Monroe Weatherwax Co. C. 2 MINN. INF.
You indicate Arbula Weatherwax Millstead is buried in South Dakota. However a search of "Find a Grave" website indicates the following:
Somerset cemetery,Somerset,Hillsdale co. MI
inscription: Arbeula Weatherwax Millstead
b: 14 Sep 1849 MI.
d: Sep 1964 SD
spouse: Ralph V. Millstead
This would seem to contradict your belief on her actually burial location.