Most likely the su-30 are received by some other unit previously operating something inferior (say J-7) which is subsequently retiredIt might replace the Su-30s. But the Su-35 is a single seat fighter aircraft which will likely be replaced with J-20.
They still have way too many older generation JH-7, J-8, etc aircraft to replace before thinking of getting rid of the Su-30 though.
“雀”It looks more like "崔" to me, which could just be his last name.