Many thanks to JC for the census info.
It seems clear that Marg d/o Thomas C/Isabella Cannell md Thompson, then Kewley and
Marg d/o Thomas C/Margaret Corlett md Quiggin, then Quayle
So we still aren't able to answer Viv's initial question as to what happened to Marg Caine Thompson Kewley

Viv, please post the marriage record of Mgt C/Thompson if you find it.

DJD