The Brazil-Russia-India-China-South Africa (BRICS) Organization recently announced that they have accepted thirteen Countries to be "Partner Countries", and of those thirteen, four are in South East Asia (SEA), namely Malaysia, Indonesia, Vietnam and Thailand.
A Partner Country is not a Full Member Country yet to the Organization, but it is definitely one Step closer to that Direction. Malaysia, Indonesia and Thailand sent their Foreign Ministers to the recent BRICS Summit while Vietnam was represented there by their Prime Minister.
Note that Malaysia, Indonesia and Vietnam have Territorial Disputes with China, arguably the BRICS' most Influential Member, and yet they have chosen to be still Part of the Organization.
Here is the Link to the Article on the Channel News Asia (CNA) Website: https://www.channelnewsasia.com/asia/malaysia-indonesia-vietnam-thailand-brics-asean-global-south-russia-china-4699841
SOURCE: Malaysia, Indonesia, Vietnam and Thailand become partner countries of BRICS {Archived Link}