Corona del Mar High's Stephania Haralabidis (USC women's water polo) and Ionna Haralabidis (USC women's water polo) smile during a signing ceremony at CdM.

Corona del Mar High's Stephania Haralabidis (USC women's water polo) and Ionna Haralabidis (USC women's water polo) smile during a signing ceremony at CdM. (Courtesy of CdM Athletics / December 3, 2012)

Corona del Mar High senior twins Stephania and Ioanna Haralabidis will be eligible to play for the CdM girls' water polo team after Dec. 31, CIF Southern Section director of communications Thom Simmons said Monday.

Dec. 31 is the end of the sit-out period for winter sports transfers. The Haralabidis sisters transferred to CdM from Greece.

"They were ineligible until we got all the paperwork that we needed to get from the previous school," Simmons said. "We have since received everything that we needed to receive from the school, and they are ineligible due to the SOP [Sit-Out Period] rule. In this case, with regard to winter sports, if you transfer after a certain date you have to sit out until Dec. 31, 2012."

Stephania and Ioanna have experience on the Greek junior and senior national women's teams. The attackers both signed with USC last month. They are currently playing with Greece in the FINA Youth World Championships in Australia.

CdM, which advanced to the CIF Southern Section Division 1 title match last year and is top-ranked in Division 1 in the preseason, opens its season this weekend in the Santa Barbara area. The Sea Kings play at No. 7 Dos Pueblos on Friday at 7 p.m., and at No. 3 Santa Barbara on Saturday at 10 a.m. CdM will also be without a top returner for those games, as Stanford-bound senior Cassidy Papa is currently playing with the United States women's youth national team at the FINA Youth Worlds.

Sitting out until January means the Haralabidis sisters also will miss the Battle of the Bay rivalry game against Newport Harbor on Dec. 21, as well as the Holiday Cup on Dec. 28-29.

Simmons said they will be eligible for swimming in the spring when that sit-out period ends April 1, 2013.

matthew.szabo@latimes.com

Twitter: @mjszabo