New Zealand thrash Sri Lanka in second T20 to level series
Seifert smashed six sixes in his 43-ball blitz as New Zealand romped home with 5.2 overs to spare to level the three-match series and gain a psychological edge ahead of Saturday's decider in Queenstown.
Auckland-born Cotton became the first female umpire to stand in a men's international match between two International Cricket Council full-member countries.
Earlier, Milne claimed a career-best 5-26 to help bowl out Sri Lanka for 141 in 19 overs, which proved below-par at Dunedin's University Oval, which has relatively short boundaries.
Sri Lanka lost their openers cheaply and after Kusal Perera, Dhananjaya de Silva and Charith Asalanka shored them up the wheels came off their innings in the second half.
Sri Lanka, who had won the opening match on Sunday via Super Over, lost their last eight wickets for 50 runs with Milne claiming three in the final over.
New Zealand's chase got off to a blazing start with Chad Bowes hitting Dilshan Madushanka for four boundaries in the second over, including three in a row, throwing the seamer out of the attack.
Seifert ensured there was no respite for the tourists even after Bowes fell as he tore into the Sri Lankan attack, sealing New Zealand's victory with back-to-back sixes.
Sri Lanka's sloppy catching did not help their cause either as they dropped both Seifert and home captain Tom Latham, who remained unbeaten on 20.