Conversion from S1 visa to X1 visa

Hello all, I am a student in Beijing on X1 and my wife was staying with me on long term dependent (S1). Now she also got admission into PhD and require now X1. My question is whether she can change/transfer here from S1 to X1. If yes please advice. I heard from one of my senior that there are some provisions for change of one visa to another here without going back to home country, which is india in my case. If there are any possible link or article also kindly let me know.