IF STAFF at PolyGram Records and Warner Music had their own hits charts, the golden oldie Changing Partners would be the smash hit of the past two months. Senior management staff from both companies appear to have been indulging in a weird game of musical chairs, constantly switching allegiances. Longtime Warner Music stalwart, Paco Wong, put the tempo into swing when he left abruptly last month after a year or so of speculations. Although mystery still surrounds his exact title, Wong is said to be taking up a top-level management position at PolyGram's new recording subsidiary, Go East. A few of his loyal followers are said to be joining him. Meanwhile, Frankie Lee, the former manager of Leon Lai Ming who is contracted to PolyGram, has taken up Wong's old post at Warner. It is another blow to PolyGram, which was rocked last week when general manager, Gary Yeung Wing-hong, left with two of his right-hand men. They are said to be joining - you guessed it - Warner Music. Can anyone blame Canto-pop singers for not knowing if they're coming or going these days?