Do you have the Australian death certs for William Kennaugh and Margaret nee Whitten? These are often very detailed and informative (depending on which state their deaths were registered).

Have just found on the Vic index what looks like their marriage (thanks to Julie for sending b.IOM entries):
WHITTEN Margaret Jane, m/1911 x2 RENNAUGH Wm Edward, Regt no.3158.
So incorrectly entered as Rennaugh, and both from IOM. You can buy this cert original image online, which should give ages, occupations, birthplace, etc.
Use the regt number to buy this at: online.justice.vic.gov.au/bdm/index-search?action=purchaseCertImage

- But the death certs are important to get as well, which as well as details of where living, children etc., should have where born and how long in Australia, name and surname of father and mother (and maiden name), with occupations, as well as other details. When you have both marriage and death certs you will be far better equipped to find the right families in the IOM.

Sue