Great find, Cass!
This shows that buried with William at Kapunda is a 5 month old infant named Richard.
SA BDM shows a birth of Richard JOSE in 1865 to William and Mary Ann (nee JENKINS) in Kapunda - and a death of Richard JOSE in Kapunda in 1865, son of Richard and Mary Ann...so error for father's name.
Both Richard and William show their last place of residence as Victoria

Sophia JOSE (d. 1860) is buried in another part of the cemetery. Very nearby is an infant Sophie JOSE and a boy named John Thomas JOSE who died aged 6 - is this the John b. 1855? No death record found for either of them.