Dennehy/Denahy family tree

Hi

I have just read a document on GENUKI referring to a ' Bellevue, of Thomas Dennehy, Esq,'

Clondulane seems to be in a similar area to where my ancestors may of come from.

I'm not sure if my Denahy/Dennehy's are connected to these but I'm hoping someone can help my find the missing connection. The name seems to have been Denahy in Ireland but changed to Dennehy in Australia.

My GG grandfather was;

John William Denahy/Dennehy b.1838? in Churchtown? Parish, Cork (died 14/12/1916 in Melbourne); married Deborah Mary Haly/Healy b.7/5/1838 (died 5/12/1921 in Richmond Melbourne). Married 15/12/1858 in Milford, Freemont, Ireland. John apparently went to work on the Haly's propery?? They immigrated to Australia in 1862. Their son Cornelius John b.31 oct 1858 in Church of Assumption, Mallow, immigrated to Australia at about 22yrs old. He was left with the Haly/Healy family.

John William's Death certificate has his mother as 'unknown Singleton'

The only Denahy/Singleton I could find is;

Cornelius Denahy/Dennehy b. 1810? In Mallow? Died 1862? In Kanturk? Married Catherine/Catharine Singleton  b. 1816?

They married 22/6/1834 in Churchtown Parish, Cork.

I have found a Catherine Denahy living in Ballybahallagh in 1853 Griffiths rego but no mention of Cornelius

Cornelius and Cath Singletons daughter Catherine bap 18 june 1835 in Liscaroll cert says they lived in Ballybahallagh, so possibly the same people. They also had a child Ellen bap.10 sept 1843 in Milford. I could not find any other children listed for them.

Hoping someone can help me find the parents/siblings of John William, or find proof that Cornelius and Catherine are his parents.

Could you suggest what I should do next as I have exhausted the subscriptions I have I think and have searched all the records at the NLI. Also put posts on various sites without success.

Many thanks

Cherie