The Duke Family Tree

I am researching the history of my family and am slowly putting together the pieces. Some of the work has been started by others - John Colman, David Parry, and Margaret Morters (who doesn't know me but knows my grandmother June Loiterton)- and I hope to be able to contribute to it.
I am researching the following names:

"Duke" from Sydney, Australia and the Isle of Man
"Colman" from Maitland, Australia and Cornwall, England
"Parry" from Wales
"Loiterton" from Cootamundra, Australia
"Hittmann"
"Devereux"

Any tips, clues, advice, corrections etc, would be greatly appreciated.