If anybody wants to change the player before the end of the season, the old player will remain in the ranking "avaiable" for another one to pick her, and the new player will start with 0 points.
But you can switch to an inactive player and keep her ranking points.
For example, I can left Selima Sfar and take Marta Domachowska, but I´ll keep Domachowska´s points, and then Macmillan can leave Keothavong and take Sfar.
At the end of the season, you can change "the name" and keep the points you earned. For example: Mirjana Lucic can switch to Anna Kournikova keeping Wojtek´s points.