Possibly Mark Eaves may have been married more than once..................
1851 Maryborough Twp, Wellington - pg 3
http://ontariocensus.rootsweb.ancestry.com/transcripts/1851/3501-index.htmlEaves           Mark
Eaves           Nelson
Eaves           Sally Ann
Eaves           Betsy A
Eaves           Mary A
Eaves           Peter
Eaves           Jeremiah
Eaves           Clarien (believe this to be Clarissa)
Clarissa/Clara nee Eaves Ellis born April 1842 Ontario passed away 27 September 1929 - father Mark Eaves born Ireland - No mothers name given.
Sally Ann and Betsy Eaves were twins both 16 years old in 1851 -
Nelson Eves born 1833 East Gwillimbury, Ontario, Canada - father Mark and mother Mary  married Jane Datchet 11 May 1859 Simcoe. Residence: Tecumseth
Peter Eaves born 1841 passed away 18 May 1875 - 
FIND A GRAVEBurial Palmerston Cemetery  Palmerston Wellington County Ontario.
https://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=96801080&ref=acomThere is a son listed - William R Eves 1868 - 1931
https://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=96801159Marriage of Peter Eves and Sarah Allison - 11 October 1860    East Gwillimbury, Ontario.  Residence:   Tecumseth -  Parents listed as Mark and Mary. 
Peter Eves and Sarah 1871 Perth North Ontario
Peter Eves   31
Sarah Eves 31
Jane Eves   8
Sarah Eves 7
William R A Eves 3 
Sandra