In my youth baseball league, we may replace the baserunner with a "courtesy" runner if that baserunner is playing catcher on defense. This lets them get back to the dugout and put their gear on a little early and help keep the game running more quickly. It's not a "pinch runner" since the baserunner will return to the game on defense (as catcher), and the replacement runner is already in the game in another position. (They're traditionally the player who was most recently put out.)
So, what's a reasonable way to indicate this on the scorecard? I think the courtesy runner's number should be the one appearing at the base they occupy, but there needs to be more to indicate why it's there since they were recently put out. I've been putting "c" after their number, but I'm wondering if there's a more accepted notation.