You can edit a conversation asset in Campaign Manager if it’s not already part of an active click-to-message ad campaign. You can't edit a conversation asset in an active campaign. If you want to edit a conversation asset after the click-to-message ad begins to serve, you must pause the existing ad and create a new one with the required edits.
Edits to the feed portion of the ad can be made while in either draft or active status. Conversation assets are only available for click-to-message ad campaigns.