Emma's father, Brian Diamond, is a well-known stock auctioneer in Wairarapa.
Mr Diamond said he and his wife Annie had known about his daughter's part on the show for several weeks but had been sworn to secrecy.
He said despite being based in Dunedin, Emma was very much "a Wairarapa girl" but secrecy regarding the show meant he could not comment further.
Now in its fifth season, the theme of the 2016 series is "Girls vs Boys".
Among the "boys" are a builder and his apprentice, from Mount Manganui.
The four teams will be renovating a group of 1980s townhouses in the Auckland suburb of Meadowbank.
The show will start screening on May 29.