Hello
.. and welcome.

As you haven't given an idea of years of birth for Henry Milne and Andrew BURT, I've found it necessary to look back through some of your previous threads.
Henry was easy enough to find - born circa 1891 ... and I see that back in 2008 on another thread, a chatter has provided "1 March 1882" as Andrew's birth date.
I notice also that the BURTs were all born in Scotland.
[It's helpful for us to have all this additional information. ]

Henry Milne BURT was married in 1920 to Eva Maud PATT
ORSON (unusual spelling - maybe the "O" is an error ?)
[Birth details for any children of this couple, won't appear online as the index only goes up to "today's date", 1912.]
Sometimes the easiest route to tracing descendants, can be by sourcing death notices from newspapers. [If this is something you're unable to do yourself, then there is generally a volunteer here, available to help out with the task.]
So firstly we should find where in NZ Henry died / is buried ?
~ Lu