问题
Do all messenger bots interact directly with just one user at a time? Can a bot join a group of two or more people and talk to them?
回答1:
Currently Facebook Messenger bots only work on a one to one basis.
One of the reasons is probably privacy.
Facebook are being very cautious before rolling out bots in a group context.
回答2:
Currently facebook does not allow to add bots in groups, however you can add bots in groups in Telegram.
来源：https://stackoverflow.com/questions/40205889/can-a-facebook-messenger-bot-chat-with-two-or-more-people-in-a-group