Include ASEAN in the QUAD?
Sorry, but Indonesia, literally the "Big Bro" of ASEAN, repeatedly stressed that they would not join any military alliance with any other country as per Indonesia's constitution.
Count Thailand, Laos and Cambodia out, all of them are in China's team.
Malaysia, despite being part of the FPDA and have maritime disputes in the SCS, would like to stay out of the US-China confrontation bullpen. They also criticized AUKUS.
Myanmar can be counted out as well.
That's more than half of ASEAN gone.
thailand, Myanmar, Indonesia and other all sent ministers to China couple days ago. Aside from Singapore going other way, it’s pretty clear to anyone that NATO or Quad in ASEAN isn’t going to work.