Well you raise Tiananmen, which is impossible to prove either way. But it is well known that people died amoung chinese (hence the massive emigration during and right after).

And now you've raised messing with Hukou, I hadn't heard of that happening, and again, you still haven't provided any sources for your info. I imagine it is extremely hard to mess with Hukou as you'd have to change birth records as well, Given china doesn't have a centralised system (for either birth or Hukou) records, it would be very complicated to achieve this.