Champs on Family Tree Circles

I'm seeking any info on the three Champion brothers John, Isaac & William who were tin miners and lived in the St Ives area of Cornwall. In 1875? they all came to Melbourne aboard the 'SS Great Britain'.
I've lost track of John & Isaac. Anybody have connections ?
William married Adelaide Nankervis in 1875? & they had two children,
(Ethel)& Albert who subsequently married Helena Watson & they became my g/grandparents.
Albert & Helena passed away in 1945/1944 respectively, after producing three sons - Norman,
Harold & Reginald. Norman & Reg had no children and I am the only son of Harold.
I have two siblings, Barbara & Diane.
I have sired Paul (1969), Lisa (1972) & Greg (1975)
Paul sired William (2000) & Emily (2002),
Lisa married Jarrod Kennedy in 2000 & bore Jack (2001), Ben (2003), Charlie (2005) & Alex (2012)
Greg sired Dusty (2006) & Maple (2008)

I do have some detail of our convict origins out of the Gangell's of Tasmania - all on Helena Watson's side of the tree & going back to 1770's The picture is of the Memorial - on Constitution Dock - to
the first settlers of Tassy who arrived aboard the sailing ship 'Ocean' in 1804

Hello you clever & dedicated researchers - I would appreciate any assistance in tracing my g/parents - William & Charlotte Chapman & their ancestors/descendants.
I am quite the novice in these searches & probably as expected, I have little info to start with:

William (2nd name Frederick?) Chapman sailed from England to Melb in late 1800s.
He served as a cabin-boy aboard the 'SS Marpesia'.
He later established a furniture/storage business at 256 Dorcas St Sth Melb. He married Charlotte Ford in 1890 & they had 6 daughters, Ada, Alice, Florence, Nell, Gladys & Win(born 17/12/1912)
Alice married Tom Brown, Florence married Reg Baillieu (of Sorrento), Nell married Tom Freeman,
Gladys married Roy Lunn & Win married Harold Champion (my parents) in 1940.

William died at his Dorcas St address in 1945 following a fall from his upstairs balcony.

The photo (circa 1915) shows L>R: Florence, Ada, William, Alice, Win, Charlotte, Gladys & Nell