Hannah Darling, Sara Kaljuvee and Nadia Popov replace injured captain Jen Kish, Julia Greenshields and Mandy Marchak for this weekend's competition in Langford, B.C.
Kish was injured on the first day of competition in Atlanta last month and missed the rest of tournament.
"If this was the Olympics she would and could play," said Tait. "That being said, it isn't, so we are being cautious on her return to competition and she will likely be back in for the rest of the series."
The three Canadian additions were with Canada's Maple Leafs team at the Hong Kong Sevens in late March. Darling and Popov were last with the women's team in Sao Paulo in February. Kaljuvee, returning from injury, is making her season debut after captaining the selects side in Hong Kong.
Canada, which has placed third at the last three events, stands tied for second with Australia in the overall standings. New Zealand tops the table with 60 points, 12 ahead of Australia and Canada. France is fourth with 28 points, two ahead of the U.S.
Canada is the fourth stop on the circuit with two more events to go.
The top four teams at the end of the season will automatically qualify for the 2016 Summer Olympics.
The Canadian women will open Saturday against Russia before taking on South Africa and the U.S.
Elissa Alarie, Ste-Anne-de-Bellevue Rugby Club, Trois-Rivieres, Que.; Britt Benn, Guelph Redcoats, Napanee, Ont.; Hannah Darling, Peterborough Pagans, Warsaw, Ont.; Bianca Farella, Town of Mount Royal, Montreal; Sara Kaljuvee, Toronto Scottish, Ajax, Ont.; Ghislaine Landry, Toronto Scottish, Toronto; Kayla Moleschi, Williams Lake Rustlers, Williams Lake, B.C.; Karen Paquin, Club de Rugby Quebec, Quebec City; Nadia Popov, Aurora Barbarians, Newmarket, Ont.; Kelly Russell, Toronto Nomads, Bolton; Ashley Steacy (capt.) Lethbridge Rugby Club, Lethbridge, Alta.; Natasha Watcham-Roy, Hull Volant, Gatineau, Que