Hi
I am a descendant of Thomas and Ann Underdown (nee Harding) of Devon, England. Their children Thomas and Robert Underdown came out to Australia. I am descended from Thomas' branch - you are descended from Robert's branch.
If you are still interested in finding out more about the Devon Underdown line, I recommend you start here -
https://www.wikitree.com/wiki/Underdown-360I am gradually adding as much detail on the family as I can to Wikitree. That link will take you to what I have added on Paddy's father, and you can keep clicking each generation back to find out more.
If you would like some more specific detail, please don't hesitate to contact me and we can private message each other.
Regards, Eramophla