New Zealand coach Gary Stead said the team supported Conway's decision.

"Family comes first in this environment and we're all really excited for Dev and his wife Kim to welcome their first child," Stead said.

"Mark was with the Test squad in India recently and returned to the Plunket Shield by scoring an impressive 276 - so it's a good time for him to be joining us."

Young was the unfortunate collateral of Kane Williamson's return from the hamstring injury that ruled him out of the India series. Williamson has picked up where he left off, with two half-centuries as the team's leading runscorer with 195 at 48.75.

However, the rest of the line-up have been found wanting, particularly Conway. A five-ball duck on Sunday dropped the left-handers' series average to 5.25.

Speaking after the defeat at the Basin Reserve, Black Caps skipper Tom Latham was coy on further changes for Friday's match at Seddon Park. The squad will reconvene in Hamilton on Wednesday ahead of Friday's match, with Latham keen to assess conditions at Seddon Park before deciding upon a different balance of XIs, having gone unchanged for the first two Tests.