This question is really just to confirm what I've read in the rules or really what is not specifically written in the rules...
USAPA rules state the following:
- 4.L. Service Foot Faults. During the serve, when the ball is
struck, the server’s feet shall:
- 4.L.1. Not touch the area outside the imaginary extension of the sideline.
- 4.L.2. Not touch the area on the wrong side of the imaginary extension of the centerline.
- 4.L.3. Not touch the court, including the baseline.
There are no rules specifically about the server's partner, but this has been a point of contention here and there in rec play.