Alexine,
A Cornelius Donovan gets a mention in the Victorian Government Gazette in a Office of Mines Notice dated 4th February 1863.
In short, Cornelius Donovan and J. M. Connell & party each applied for a reward for discovering a gold field at Walshe's Creek or Donovan's Creek.
A possibility, although David would have only been around 18 in 1888.
1888 Wise Victorian PO Directory
Donovan Cornelius, farmer, Alexandra.
Donovan David, farmer, Tyaak.
1904 & 1914 (Wise) Victorian PO Directories have a David Donovan still as a farmer at Tyaak.
Regards
Gerry