Wow! You've all been so busy while I've been in bed! Can't say how impressed and grateful I am for everyone's interest and help.
The Lavery/Morrow puzzle seems clear now, if I could get hold of the death certs of John Lavery and Margaret (Morrow) in Australia, I'd be home and dry.
If John married Margaret in NSW in 1870, then he was a bigamist as well as an absent dad since the first Mrs Lavery, Ann (Warnock) didn't die til 1872 in Barnhill. The saddest bit about her, apart from her occupation as a "stickbreaker", was that no-one even bothered to put a cause of death on her certificate. One of their children, David, "pauper",died aged 10 in East Park Cottages.
You are spot-on, Joekar, with the Warnock link to Mary Lavery Reid. She married my GGrandfather, William Reid, in 1887. That is my direct line - my maiden name is Reid, and that is why I'm so interested in the fate of my GGGranny Ann and my errant GGGrandfather John Lavery. The Nisbet connection threw me a bit, I wondered why they started appearing in census entries, til I found the remarriage.
I'll need all morning to digest and write out all the info which you've all provided. Bang goes the housework!