O'Hea averaged 4.8 points, 1.7 rebounds and 1.4 assists in 39 games last season, when she split time with the Sparks and the Australian national team at the London Olympics.
She is currently playing in Australia for the Dandenong Rangers, averaging 14.7 points and 6.1 assists.
Ferrari has played professionally in Spain, Ecuador, Argentina, Paraguay and Peru. Last season she averaged 17.1 points and 3.6 rebounds in 25 games with Soller Bon Dia in Spain. Ferrari is currently playing for Perfumerias in Spain.
The Sparks open the WNBA season on May 26 against Seattle.