The pair’s unbeaten 69-run fourth-wicket stand helped Australia A reach 3-179 at stumps, with a lead of 115 runs going into the final day at Cricket Central.
They came together with Australia A in a precarious position at 3-110, having lost openers Maddy Darke (18) and Tahlia Wilson (30), and Anika Learoyd (29).
Trenaman’s innings continued an impressive match for the 23-year-old, who was Australia A’s top scorer in the first innings, leading the way with 77.
Earlier, England A resumed trailing Australia A’s first-innings total by 26 runs, a gap they quickly closed as Paige Scholfield continued her superb innings.
Having resumed on 138, Scholfield continued to frustrate the hosts, adding a further 26 runs to her overnight total before she was finally caught behind on 164.
A series of handy lower-order contributions helped extend England A’s advantage as they batted through the morning session, with Georgia Davis (23) and Eva Gray (14) ensuring their lead was 64 when the final wicket fell.
Tess Flintoff led the way the ball, taking three wickets, while Lauren Cheatle, Maitlan Brown and Lilly Mills claimed two apiece.
The four-day match is the final game of England A's multi-format tour, with the Aussies winning the preceding one-day leg 2-1 and the visitors the rain-affected series-opening T20 leg 1-0.
