George and Elizabeth Youngson

is my ancestor and she and her brother George were transported on the first fleet and arrived at Sydney Cove on 22/1/1788. Elizabeth and George were later transported to Norfolk lsland on the Supply. I couldn't find their names on your list of convicts transported to Norfolk Island. Elizabeth apparently had a child to a free settler by the name of John Piper? She also had 2 more children but not sure who the father/s were.
Elizabeth and George were returned to Sydney in November 1794 without the children.
Could you please clarify if this information is correct.