Hi Maureen , had another look at Brian Lawson's index of IOM census for Elizabeth and Margaret , there are about 6 possible Elizabeth Gill/Gell/Gale and 3 Margaret Caley/Coley , but none together , so the damaged Manchester records could be right. However normally when the Manx left the IOM they went to Liverpool , have you looked for Liverpool ?
The NSW State Archives shows it has two reels of Information. I will be going there soon , so will look to see if there is further information.
Cheers
David