Sarah Jessica Parker on the set recently

Sarah Jessica Parker and Cynthia Nixon are desperate for their two sons to have a playdate.The actresses are both currently filming the 'Sex and the City' movie and want Cynthia's four-year-old son Charles, and Sarah's five-year-old boy James to become friends.Cynthia - who also has an 11-year-old daughter, Samantha - said: "If we're shooting late on a Friday night, they'll come by the set."But James and Charlie seem to be on set different days. But we talk to Charlie about James and James about Charlie, and one day we'll figure it out so they can be there at the same time."The flame-haired actress - who split from the children's father Danny Mozes in 2003, after falling in love with education activist Christine Marinoni - also revealed she encourages Samantha and Charles to give money to charity.She said: "My children are being raised Jewish, so last year we all had a meeting with a rabbi, who said it's good to let your children know what their parents values are."Despite her wealth and fame, Cynthia refuses to send her children to private school.She added to People magazine: "I'm a very big public school advocate. I try to bring public awareness to increase funding. My kids go to public school. I grew up in New York, went to public school, got a great education. It wasn't a tough decision."