How can you generally prevent a subgroup "deciding the content that should be written on the main channel for the benefit of outsiders asleep in other time zone

How can you generally prevent a subgroup "deciding the content that should be written on the main channel for the benefit of outsiders asleep in other time zones" even in an 'asynchronous' communication channel? There's nothing stopping them from responding to each other quickly enough to effectively communicate 'synchronously'. I've intended to reply to communications before only to discover that someone else replied first while I was asleep in my other time zone.