Reese Witherspoon and Christina Applegate played Rachel's sisters on Friends, but they never appeared together because Rachel was never intended to have two sisters. Witherspoon's character, Jill Green, was introduced in season 6 but wasn't brought back, leading to speculation of a feud with Jennifer Aniston. However, the tension between the actresses was denied, and Witherspoon couldn't return for season 9 due to a scheduling conflict, so Applegate played Rachel's other sister, Amy. Both actresses enjoyed their roles and deny any issues between them.
