They dominated possession in the first half through strong running from their forwards and several times came close to scoring.
It took a solo effort from halfback Augusta Livuana who barged her way over to near the uprights one minute from half time.
Livuana added the extras to take her team to a 6-0 lead.
A misread in play in Tarangau’s own 10 metre line allowed Sisters to pounce on the ball and in the very next play pass out wide to a flying Sandy Molumi to score early in the second half.
Tarangau finally got things going midway through the game when an inside ball saw Kylie Gabriel cross the line.
A missed conversion attempt left the progressive score at 10-6.
But hooker Mantex Pala sealed the win for Sisters and did it style with a runaway try that saw her dash 40 metres to score.
In other women’s results, Souths defeated Butterflies 4-0, Royals were too strong for the Kone Storms winning 14-0, Paga Panthers did it easy beating Kone Tigers 12-0 and Magani downed Wests 10-0.