Slavin family in Australia - HELP needed

Is there anyone doing researching on the SLAVIN family in Australia.

I have very little details other than what I have stated below:

• My ggrandfather was Francis Slavin who married Betsy England in Wellington NSW in 1875. (The wife's family ENGLAND is large and live at Neurea / Baker's Swamp, approx 12 miles out of Wellington on the Molong Road) 
• Their marriage certificate states Francis' age as 28 and his parents as Edward Slavin and Maria Callaghan, it states at he was born in Melbourne Vic. I have no luck with this guy.
• I have no record of birth, no record of death for Francis Slavin. I have checked with funeral directors records through historical society without success. He is not buried in Wellington, even though his wife was. Betsy and Francis' last child was born in Wellington area in 1890. 
• Francis and Betsy's children were Edward, John, Arthur (grandfather), Theresa, or Thurza and Emily (1890). 
• I am waiting for birth certificate of Arthur...i must say, eagerly. It has been strange that Francis has never been talked about in the Slavin/ England family. 
• My grandmother Lucy England (b.1898) married her first cousin Arthur Slavin (b. 1878) but did not know anything about Francis or had heard any conversations about him, even though Francis was her father-in-law and also her uncle through marriage) 
• Can anyone help me identify an Edward Slavin entering Australia, possibly through Melbourne Vic, Francis' birth and death or anything else which would break through this brick-wall I have had for years.