The correct answer is:
Kaitlin and her partner were allowed to stand on the same side of the court during the return of serve.
From ITF Rule 8:
Rule 8 says that “the receiver may take any position inside or outside the lines on the receiver’s side of the net.” That means that both doubles partners can stand anywhere on the court during a return of serve as well. If the server is unsure which partner is receiving the serve on the first point of a set, she should ask who is taking the serve to clarify any confusion that may arise.
Here's how our readers responded: