At the coming (epi th parousiai). At the coming here of Stephanas, etc., the very word used of the parousia of Christ ( 1 Corinthians 15:23 ). That which was lacking on your part they supplied (to umeteron usterhma outoi aneplhrwsan). Either "these filled up my lack of you" or "these filled up your lack of me." Either makes perfectly good sense and both were true. Which Paul meant we cannot tell.