People may not realise it but Chinese claims over the South China Sea are really that, Chinese. They predate the PRC and as such are the same on both sides (PRC and ROC/Taiwan). It just so happens that overall only the PRC is strong enough to assert them in full.
There is an interesting dynamic going on between Vietnam and China in the SCS. 30 years ago it was very antagonistic (they fought a brutal border war in the late 1970s, and a naval battle in the late 1980s), 10 years ago it was very nationalistic, and now the leadership is more aligned, owing in large part to Beijing's effort to leverage its economic might to further its territorial claims in the SCS and geopolitical goals, which include countering the US influence in the region and annexing Taiwan.
There was a similar move to work with the former Duterte administration in Manila despite competing SCS territorial claims although the pendulum seems to have swung the other way in recent years.
