Separate names with a comma.
Is that possible?
As far as I'm aware, only by having a guild member actively in the game able to receive chat messages and recording them using a mod of some kind.
Not that I’m supporting it, but the best option is to create a Guild Bot using an MC Protocol library (such as Mineflayer for NodeJS) and then parsing messages that start with “Guild > ”.
Guild Bots specifically fall under a gray area of the rules, but you can take precautions like making sure it instantly teleports to Limbo when joining and ensuring that it only sends messages in Guild chat.