Yapp has included 20 players for the upcoming fixtures who featured in Australia's WXV 1 and O’Reilly Cup competitions last year with a further nine potential debutants also included in the 30-player strong squad.
Head coach Jay Tregonning has made one change to his starting XV from last week's victory over France as the Wallaroos prepare to face Wales in Auckland.
The six teams have been named ahead of the first round of WXV 1 in Wellington. All matches will be played at Sky Stadium, kicking off with England vs Australia on Friday 20th October. On Saturday 21st October Canada will face Wales before home side New Zealand take on France in a RWC2021 semi-final rematch.
The Australians open their campaign in Wellington against England on Friday night, followed by matches against France and Wales.
Michaela Leonard will lead the Wallaroos on a four-Test tour of New Zealand while regular captain Piper Duck recovers from ankle surgery.
Wallaroos captain Piper Duck is set for her first appearance in the Pacific Four Series after being included on the bench to face Canada in their final match of the tournament.
Australia went 0-3 in last year's Pacific Four but saved their best performance for the Americans, charging home with two late tries to fall narrowly short and lose 16-14.
Michaela Leonard will captain the Wallaroos for the first time later this week when Australia host Rugby World Cup champions New Zealand in Redcliffe.
Queensland prop Bree-Anna Cheatham has been parachuted into the Wallaroos starting side, making her Test debut against New Zealand in Christchurch on Saturday.