As for GNU Social (I wasn't sure whether you meant that or Pokemon Gold and Silver), no multi user replying, at least not aware of it being a thing.
Because no button for that exists in the default UI, but I can still see "🌲Number 1 Pleroma Criminal on XBL 🇵🇱|🇺🇸 in reply to 寮, Terminal Autism" showing up, so I do suspect that the functionality for multi user replying does exist.