*Club domestic league appearances and goals, correct as of 10:23, 13 February 2021 (UTC) ‡ National team caps and goals, correct as of 10:23, 13 February 2021 (UTC)
Sister has played for South African club Liverpool Ladies in the Eastern Cape Sasol Women's Football League.[3][4] In 2015, she signed for Hungarian Női NB I club Győri ETO.[4][5] She signed a two-year contract, and became the team's highest earning player.[4] Sister made her debut against Kóka KSK; Győri ETO won the match 3–0.[6][7] In 2016, Sister signed for Italian Serie A club San Zaccaria [it] on a two-year contract.[8]
Sister scored a goal in a warmup match against Cameroon prior to the 2012 African Women's Championship;[15] she had missed two previous games against Zimbabwe to rest an injury.[10] At the 2012 African Women's Championship, Sister failed a drug test. She was suspended until 16 December 2013;[16] originally, she was given a two-year ban, but that was reduced to one year by the Confederation of African Football (CAF).[17] The doctor who administered the drug admitted responsibility,[18] and was subsequently banned for four years.[17]
Sister returned to the national squad in 2014.[3] She was not selected in the South African squad for the 2015 African Games in the Republic of the Congo, as Sister was finalising a move to Győri ETO.[5]