Despite calls for a three-game series that mirrors the men's, the women's Origin series has been expanded from one game to two this year, creating the very real possibility of a tied series after the second match in Townsville on June 22.
Players had initially been told that in the event of 1-1 series, reigning champions NSW would retain the shield.
The men's series used a similar retention principle prior to the introduction of the golden-point rule in 2003, with reigning champions Queensland awarded the shield in 2002 after the 1-1 series ended with a drawn third game.
But with the women's Origin sides already in camp on Thursday, the NRL informed both of a change that would come into effect from the series opener at CommBank Stadium on June 1.
In the event of a tied series, the winner will now be decided on points aggregate across the two games - an option the league had initially rejected.
If the Maroons and Blues score the same number of points as one another and the series is tied, the side with the most tries will be declared the winner.
The changes are set to favour Queensland, who had previously only been able to clinch the two-game series with a 2-0 whitewash.
Speaking at their Homebush training base, NSW players insisted the changes had not changed their hopes of completing a clean sweep of their own.
But 18-year-old Southwell, who will make her Origin debut in the halves, admitted the 11th hour response had taken her aback.
"We want to win both games," Southwell said.
"But I was a bit shocked that they announced it the day we got into camp.
"I thought that was a bit disorganised and a bit disappointing from the NRL, because we've been told for months that if we win then we retain the shield.
"I think that's disappointing from the NRL to see that they're not organised and they don't value the fact that we need to know before we get into camp.
"It was that afternoon as well, it wasn't even the morning."
Blues second-rower Yasmin Clydsdale preferred the change to the previous system of shield retention but said the women's players were united in their desire for a three-game series.
"Every year, the squad's different," she said.
"I don't want it to be a reflection of last year, I want it to be a reflection of this year and where the game's at.
"But again, I think as female athletes, we should still be fighting for the three games."
Speaking on Friday in his role as a Nine Network pundit, Canterbury football manager Phil Gould said the Bulldogs' training ground Belmore Oval could be used as a location for the decider if the series was tied. Clydsdale was heartened by the offer.
"If we get to that point, maybe that could be a conversation in the future," she said.
"I love to see that everyone's feeling the way we're feeling. We are frustrated (with the two-game series).
"But again, in the NSW camp, we're focusing on winning 2-0."
