Hi
I have been looking at Annie Unwin(Reid) and noticed Ann Unwin with a death date of 1906. I also found a marriage of Annie Unwin in Kaiapoi in 1886 in Papers Past.

MARRIAGE.
Star , Issue 5491, 7 August 1886, Page 3
Unwin? Vette.-- August 5, at St Bartholomew's Church, Kaiapoi, by the Rev J. W. Stack, Annie Unwin to John Henry Frederick Vette, Ohoka.

What do you think?
I haven't found a death date for Annie Vette though.

Google "Everything Unwin" - they are a set of blogs about the Unwins, that I have written. Annie Unwin married Henry Vette (thats what my Grandfather called him) after Thomas died. I don't know why she was registered in deaths as Unwin, but they are definitely the same person. Ohoka is just out of Kaiapoi. Perhaps she was buried in the Anglican cemetery with her first husband, and the three dead children of hers that were there also; and if that were the case, then perhaps that is why they registered her death as Unwin. Quite an anomaly that I pondered over for some time.

Thanks for confirming that and your blogs have been a great help. If I find anything useful I'll let you know.
My husband is 3rd cousin to your father.