Following recent performances three further combinations have been added to the list, including Joe Meyer and Ease On Fire, Mark Todd and Gandalf, and Dan Jocelyn and Mr Pracatan.
Missing from the original list are New Zealand-based duo Matthew Grayling and Bryce Newman, both forced to withdraw from contention after their respective horses were injured.
Todd, a double gold medallist, recently achieved the Olympic qualifying criteria to make the final cut-off after making a late bid for Games selection.
The UK-based Dan Jocelyn competed at the Athens Olympics where the New Zealand team finished fifth.
The complete shortlist is:
Andrew Nicholson - Lord Killinghurst and Henry Tankerville
Annablel Wigley - Black Drum
Caroline Powell - Lenamore and Mac MacDonald
Dan Jocelyn - Mr Pracatan
Emily Butcher - Southern Ben
Joe Meyer - Snip and Ease on Fire
Heelan Tompkins - Sugoi
Mark Todd - Gandalf
Team manager Blyth Tait, a former Olympic and world eventing champion, is pleased with the depth of talent in the New Zealand ranks.
"All eight are worthy candidates who have shown good performances at a top level, giving us more experience to select from going into an Olympic campaign than we have had for a long time," he said.
The final team of five to compete in Hong Kong will be named in mid June.