Karzem also began coming to the Wanganui festival aged 11, but this is her third time in the River City.
"I'm really looking forward to the Australian trip," Karzem said.
School cricket in Auckland whetted her appetite for the game, while Van Tilburg was encouraged to play the sport after her older brother made the representative side in Auckland.
The Auckland U15 side went down to Northern Districts during the first 30-over match on day one of the festival on Tuesday, disappointing both girls.
The official score was Northern Districts by three wickets but in reality it came down to just three runs in the last over.
"We should have won that match," Van Tilburg lamented yesterday.
The day two morning session yesterday was far more satisfying for the Auckland openers.
Under the rules of the 30-over festival matches, they were both forced to retire after scoring 50 runs, with Van Tilburg chalking up her 50 from just 52 balls.
Being two years younger, Karzem has yet to reach the heights of her older rep teammate but she is still regarded as a serious up-and-comer in cricketing circles.
Van Tilburg, however, has been making the headlines for several years as a natural sportswoman.
In her time at Glen Eden Intermediate in Auckland, she was involved in 17 sports and was named Year 8 sportsgirl of the year.
As a Year 10 Avondale College student, she made her mark in several sports, with cricket her real success story.
She captained the school's 1st cricket X1 last summer, showing out as a more than useful performer whether batting, bowling or even keeping wickets in guiding her team to the semifinals of the girls' schools competition where, without the team's other star player, they lost to St Kentigern.
In the schools competition, Van Tilburg bagged 11 wickets at an average of 11 and scored 295 runs - at an average of 295 - and was dismissed only once.
Despite her hectic schedule, she says she does okay academically.
The Wanganui Festival of Cricket continues at Victoria Park today and tomorrow.
Results from day one: Wellington U15 beat Canterbury U15 by 8 wickets.
Taranaki secondary beat Wanganui secondary by 126 runs
Manawatu secondary beat Central Districts U15 by 34 runs
Northern Districts beat Auckland by 3 wickets