• Start a Facebook conversation from a comment: POST /v1/conversations now accepts a Facebook comment id for a Facebook Page account, sending a private reply to the comment's author. This lets you kick off a direct message with someone right after you receive a comment webhook, the same workflow already available for Instagram. Replies sent more than 7 days after the comment, or to a comment that already has a private reply, are rejected with a clear error so you can handle them in your app.
• Conversations continue naturally after the first reply: once the commenter responds, their message arrives like any other conversation message, and you can keep replying through the same conversation for 24 hours, just as with Instagram.
• New permissions required for Facebook messaging: to use this feature, reconnect your Facebook Pages with the pages_messaging and pages_manage_metadata permissions so replies can be sent and follow-up messages can be received.