The union announced three further signings yesterday.
Backs Isaac Te Tamaki and Rory van Vugt, and forward Charles Alaimalo have all signed contracts for through to 2021.
Head coach Dale MacLeod said it was a good outcome for the province.
"All these men have huge potential, and to have them committing to Rugby Southland for another two years is great for our game," he said.
"It shows they believe in what we are doing and the direction that we are heading in. All three have the potential to play super rugby."
For van Vugt (22) and Te Tamaki (24), it will be their third season back with Southland.
Te Tamaki and his partner Anataia have called the region home since 2018, while van Vugt made the trip down from South Otago in 2018 for a call up in the Stags Mitre 10 Cup set up.
Since then both players have proven their worth. Te Tamaki has put in some standout performances at wing and centre.
Alaimalo joined Southland from the Waikato in 2019. He was recently named in the 2019 Southland Sevens squad.
At just 20, he proved during the 2019 campaign that he was a player of real ability, playing big minutes for a young player. A Super Rugby contract remains a firm goal of his.
MacLeod is confident the eight other contracts that have been offered will be signed before Christmas, bringing the signings to 18.
Stags squad for 2020
Forwards: Ethan de Groot, Manaaki Selby-Rickit, Ray Tatafu, Charles Alaimalo, Matt James, Lio Tosi.
Backs: Ray Nu’u, Isaac Te Tamaki, Rory van Vugt, Josh Moorby.