A couple of questions I've had rattling around in my brain, based on some of the stuff that could come up from the China split and the existence of the Guangdong Special Economic Zone.
1) How does the China/Guangdong split happen and what does the end result look like?
2) What would losing a large chunk of industrial capacity (with the Guangdong defection) do to civilian cohesion and the one party state?
3) How much of 'China' survives the split?
4) Does mainland China become a series of warring regional states that then declare themselves as nations?
5) What implications does the instability caused by the Guangdong split have on internal stability within China (e.g.: Hong Kong)?
6) The relative strength of China vs Guangdong might also depend on who controls Manchuria? Does Manchuria become its own nation state in the chaos of the split?
7) What implications does the China instability have on surrounding nations (e.g.: India, Burma, Pakistan, the Korean peninsula, Japan, Bangladesh, Nepal, Philippines)?
With the rise of Guangdong, I could see alignment and polarization towards it (instead of 'China') for some of the South and South-East Asian states (i.e.: Burma, Tibet, Nepal, Bangladesh, Vietnam). Pakistan might go either way and whichever way it went (China or Guangdong) would have further ripples for Afghanistan, Iran, India, the Stans and Sri Lanka.
The existence of potentially two strong Chinas on its northern border (China and Guangdong) could also cause a fracture in the Indian state along the Northeast Frontier (Siliguri corridor). It'd also have ramifications for the Naxalite corridor (i.e.: Nepal, Tibet, Bangladesh, Burma) and probably Arunachal Pradesh ('East Tibet').
Some of these I'm not going to definitively answer just because I'm far from an expert on Chinese culture, history, and governance, and as such have not filled in every detail of how the people of China would react to the events of the world.
1) Like the US, the main government of China was dismantled during the Bactaran occupation. After the occupation, more localized governing bodies formed on an ad hoc basis, and it was these local governments which made the decision whether to join the PCEG and UEN respectively. Of these, Guangdong was the only one* which decided not to join the UEN, as they determined that their manufacturing and economic power could be leveraged better if they were independent. The other provinces, not having the same clout as Guangdong, joined the UEN.
* Probably the only one. This is one of those culture things I don't know well enough to say definitively, e.g. if there are any particular regions of China that would be more inclined towards establishing non-aligned states.
2) This one specifically I can't answer very well.
3) Culturally, most of the citizens of the provinces that came out of China would still consider themselves to be part of "China", but there is no longer a single particular nation called "China". It gradually transitions to mean more of a regional term, a little bit like "the Midwest" in the US.
4) It takes some recovery time after the occupation ends for any state to build up enough military force to consider going to war. When this does happen there are some territorial wars among Chinese provinces (and elsewhere), but generally when this happens the power imbalance is significant enough that wars are short and decisive. Ultimately, these skirmishes are pretty minor.
5) Addressing Hong Kong specifically, it legally becomes a part of Guangdong. HK's culture remains pretty unique within China, but it's less set-apart than it is in present day.
6) Can't answer this one very well.
7) A lot of surrounding nations have their own instability and recovery to worry about for a while, so cleaning up after the occupation has a bigger effect on them than effects from China. India got hit harder than most countries during the occupation, between mass driver strikes (to take out resistance cells) and higher fatality rates from the pandemics of the era. Korea (which was "unified" during the occupation, though a massive cultural rift persists) also got hit hard, with large parts of Seoul being razed. The most untouched neighboring country was the Phillipines, which was mostly ignored by the Bactarans due to their island status and came out as a stronger relative power as a result, and the Phillipines became one of the non-aligned states.