pretend to play the Yu (a wind instrument) in order to make up the number for an orchestra -- to be included in a group just to fill in a vacancy; act as a stopgap; be dragged in to swell the total; fill a post without real qualifications; hold a post without qualifications; just fill up a vacancy; make up a number without active work; pass oneself off as one of the players in an ensemble -- to be there just to make up the number (used of incompetent people or inferior goods); put in men who cannot work:
I am not good at singing. I'm here just to make up the number.