Playing doubles indoors, my partner returns a sitter from the baseline which the opposing net man pounds hard angled toward the side netting. It bounces high over the screen separating courts, but as the side netting isn't pulled all the way back at his end of the court, he runs around the end and lobs the ball back over the screen into their court. He didn't interfere with play on the adjacent court as they were in the midst of changing sides. It is perfectly legal of course to retrieve wide balls from the adjacent court in outdoor play where there is no netting separating courts, but indoors there is normally a barrier. Our opponents stopped play and suggested we play a let, which we did and lost anyway. Was this return over the screen separating indoor courts still in play?