The information I have found to date regarding the three youngest children living with Charles Reeve in 1880 is very confusing:

• they are identified as his sons, but would have been fathered during his 50's.
• there is no wife in the home.
• the "birthplace of parents" info seems quite scupulous - it correctly put Ellen in NY, it change to Wis for Montrevill, and it changes the mother for Anna, Adeline, and William (who were by the second wife). Given this it is noteworthy that the last 3 children show a French father and Wisconsin mother!
• in 1905, Ellen Reeve and Alvin Cook have step-son Clarence Reeve living with them! Where is he in 1880?
• on Edmunds marriage and Georges death, it gives their parents as Ellen Reeve and Charles Reeve!
• (. . . think there is more but cannot remember right now)

To me, the most logical conclusion is that Charles second wife - Mary Ann - died or left him sometime between 1870 and 1880. William is probably her last child with Charles. At some time after that Ellen took over as the homemaker. The three yougest children are probably Ellen's children. Perhaps she was married during the 1870s or perhaps not.

I think Charles adopted Ellen's 3 children when she took over his household. The adoption may have been formal or informal, but the children always seem to have carried his name.

It is possible that Charles had a third wife, named Ellen, during the 1870s. However, that leaves 1905 Clarence unaccounted, and does not explain the "French" father. If you assume that Chubby E is 1905 Clarence, then the only data not answered by this solution is the "Wisconsin" mother. Ellen is often reported as born in Wisconsin, although not in the 1880 census. I am bothered that they would get it right in one place and wrong in another. However, until I can uncover futher evidence, I am going to reflect this theory.