A modmail cog that works through DMs and only DMs.
You set it up so you set the roles that will receive all the DMs the bot gets, then any one of those mods/admins can just reply to the DMs sent to the bot via the DM window right there. Everyone with that/those roles can see what the other is saying and what the member who’s dming the bot is saying.
You’d think this would exist, but i’ve even searched other self-hosted bots to see if anything was out there.