This sounds right, yes. John was a Railway Surfaceman for Caledonian Railways before leaving Scotland and one of their children was called Edward who was only a school child on emigrating.
I thought I may have a match for both their deaths but haven't seen certs; Edward in 83 Norwood St, Dunedin in August 1977 amd Elizabeth (Lizzie) on 8th February 1970 in Rawhiti St but no hard proof. Lizzie's parents should be easy to confirm as they are Horatio Nelson Weir and Elizabeth Henderson. John's are Edward Green and Margaret McManus.
Thanks so much, all pointers very welcome indeed
TW