The lack of coverage at centre strongly influenced selections for the four-test series, which begins in Auckland on Thursday night, with young midcourters Sam Sinclair and Whitney Souness included in the 12-strong line-up because of their versatility.
Kayla Cullen appears the obvious candidate to provide back-up at goal defence, but Southby is mindful that the athletic star needs to first "find her groove" at wing defence as she returns to fitness following knee surgery in the off-season.
Despite the urgency in needing to find solutions to the positional shortages, Southby said she is conscious of not pushing combinations that aren't ready.
"We don't want to be stupid about it and do it at the expense of throwing people in the deep end. It's about making sure that the players when they're running in training they're showing that they're ready to get out there and do battle against the best in the world," she said.
"We're certainly very aware we have to give people time to build their confidence, so we'll be looking to [try new combinations] where we can, and if it comes off, that's good. If it doesn't then we have to try and find other ways to do that, but certainly in our trainings we have made a concerted effort to give players time in those positions."
Australian coach Lisa Alexander is in similar position to her New Zealand counterpart, with the Diamonds also looking at new combinations - some through design, some forced - over the upcoming series.
Along with the planned changes to the shooting end, in which goal attacks Tegan Philip and Gretel Tippett have been swapped out from the Quad Series in favour of Susan Pettitt and Steph Wood, Alexander has made a tweak to her midcourt, dropping vice-captain Madison Robinson.
With experienced stars Sharni Layton and Laura Geitz out of action this season, the Diamonds are also bedding down new defensive combinations, leaving Alexander with a lot to juggle.
"Watching what Janine is doing with the team you can see that she is trying to find a group that is flexible and adaptable in their positions," said Alexander.
"I'm trying to do the same things with our team, that's why I've said previously this is going to be an exhausting chess game. We'll each be moving players around a bit, which will frustrate the traditionalists of the game, because they always like to have their top seven."
Constellation Cup
Silver Ferns v Australia
Test 1: 7.45pm October 5, Spark Arena, Auckland
Test 2: 2.15pm October 8, Horncastle Arena, Christchurch
Test 3: 9.30pm October 11, Titanium Security Arena, Adelaide
Test 4: 5.00pm October 14, Qudos Bank Arena, Sydney