Family trees on Ancestry, MyHeritage, FamilySearch, etc without sources (official or from relatives) are often unreliable, unfortunately.
It seems that Diana/Dinah Tapper/Stilling had been using her husband's name to buy goods after all.
Otago Daily Times, Issue 2065, 17 September 1868, Page 2
In the case Walls v. Stilling, a claim of L4 16s, for goods supplied to the defendant's wife, judgment was given for the defendant.