Thanks to all that replied.
This gives me something to move on with.
I had assumed different parents for my grandmother. How easily we are lead on the wrong path!
Now, after receiving a printout of a marriage cert. from New Zealand the correct (hopefully) info is the right path.
I have traced many generations from my father in Yorkshire and mother's father, New Zealand to Cornwall, but the Scotland line has been the most arduous, mainly to my Nana's secret life.
She came to New Zealand in 1920 with, we are assuming a different Christian name from her birth name. Anyhow, onward!
Cheers,
Debbie downunder:)