Isabella Sutherland and Edward Wild

The Isabella Sutherland who is died on 25 August 1889, and who was buried at the Bolton Street (formerly Sydney Street) Cemetery, was aged 55 years of age at her death (as per NZBDM registrations).  This would indicate that she was born around 1834.  Nathaniel Sutherland's sister Isabella was apparently born in 1808, which would make her too old to be the Isabella Sutherland who died in 1889.  I don't believe they were the same person.

Isabella Sutherland came to New Zealand with her brothers, Nathaniel, Daniel and John on the barque Jane, which arrived in Port Nicholson, New Zealand on 24 May 1841.  She would have been aged about 33.  

I have searched early marriages, and have found one marriage for an Isabella Sutherland, to Edward Wild in 1841.  This would seem most likely to be the correct Isabella Sutherland - Nathaniel, Daniel and John's sister.  I'll need to collect more evidence to confirm this, but proceeding on this assumption...

Isabella Sutherland (1808 - 18 July 1872) married Edward Wild in 1841.   Isabella Wild is buried in the Bolton Street Cemetery - plot 47.0.  The cemetery records indicate that she was buried on 21 July 1872 and that she was 64 years old at the time of her death - which puts her birth date as the correct one for Nathaniel's sister, and tends to confirm that she is the 'right' Isabella.  Isabella and Edward lived in Murphy Street, Thorndon at the time of Isabella's death.  I am unsure when Edward died, but given that weeks after Isabella's death, her furniture was being auctioned by local auctioneer, Mr R.J. Duncan, it would seem that he predeceased her.  Having perused Newspapers around the time, I think Edward may have even died prior to 1866, but I can't find his death or burial record.  Unfortunately, like Alister's grandfather, John Waters Snr, he seems to have just vanished.  

On 4 September 1872, Mr Duncan was also advertising, in the Wellington Independent, the auction of Isabella's property, which sounded pretty substantial:

THIS DAY, WEDNESDAY, 4th SEPTEMBER.

MR R. J. DUNCAN will sell by public auction, at the stores of J. Dransfield, Esq, Grey street, at 12 o'clock sharp, Land and Merchandise as under Lot 1. Consisting of all that piece of Land about of an acre (more or less) having a private read from Murphy street, being part of town section No 586, together with 10 roomed cottage thereon, formerly occupied by Mrs Wild. The garden is perhaps one of the best stocked with fruit bearing trees of any in or adjacent to the City, and has yielded a considerable yearly amount to the late proprietress. Adjoining is a lease-hold property with 14 years to run at a very moderate rental, having a frontage of 40 links to Murphy street, by a depth of 513 links. This desirable property is situated in the neighborhood of the residences of the Hon. the Premier, A. de B. Brandon, Esq, Colonel Gorton, &c, &c, and possesses many claims upon the attention of those anxious to secure a building site in the city, or as a highly remunerative investment. 

I highly suspect that Edward and Isabella didn't have children, or if they did, that they died young, as I can't find any indication of a family.

I believe that this Isabella is the correct one.  I also note that Murphy street was just around the corner from Pipitea street, where Nathaniel and Marion Sutherland were bringing up their family.