"It's a great opportunity for them to grow with back-to-back tournaments. They're both young, exciting rugby players who bring different dynamics to the team.
Terina is a forward with great leg speed and Janna is very physical around the contact and at the clean out so in 2016 we thought this was something we needed to look at."
After finishing third at the recent Sao Paulo Sevens, New Zealand is second equal with Canada in the series, behind Australia.
The team has been drawn in Pool C at Atlanta and will play USA, Japan and Spain.
Horan said a key goal for the two upcoming tournaments was to achieve a top three season ending place to ensure the team secured a favourable seeding for the Olympics in August.
"The focus for 2016 was getting the squad ready for Rio and it would be great to win the World Series.
Australia has jumped ahead pretty dramatically which is great for the game, but we believe 2016 is not going to be remembered for the series, it's going to be remembered for Rio. Our focus is to get a quality squad with depth that can do the job in August."
New Zealand Women's Sevens squad for Atlanta, USA and Langford, Canada
Michaela Blyde (Taranaki)
Kelly Brazier (Bay of Plenty)
Theresa Fitzpatrick (Auckland)
Sarah Goss (captain) (Manawatu)
Tyla Nathan-Wong (Auckland)
Shiray Tane (Hawke's Bay)
Terina Te Tamaki (Waikato)
Ruby Tui (Canterbury)
Janna Vaughan (Manawatu)
Stacey Waaka (Waikato)
Katarina Whata-Simpkins (Wellington)
Niall Williams (Auckland)
Selica Winiata (Manawatu)
Portia Woodman (Counties Manukau)