I'm looking for any documentation that attaches Emma Anna Cantril (B 1861)to Mary Belle Cantril (B-1853). I have assumed they are sisters for various reasons, but primarily because they are listed as neighbors in the 1880 Census in Washington, Iowa. I am unable to find either of them in the 1870 Census. Also, I have seen them listed as sisters on several other public trees, but no-one else seems to have any supporting documentation. Does anyone have anything to corroborate this hunch?