When you connect a new Airbnb to Host Tools, any listings you co-host will not import.
This is because, unfortunately, Airbnb does not allow co-hosts to manage their listings via a PMS (property management software), like Host Tools.
Co-hosts can use Host Tools, but will need to get the login information from the owners whom they co-host for. The owner's Airbnb accounts will need to be linked to the Host Tools account of the co-host. Luckily, you can connect as many different Airbnb accounts as you'd like to Host Tools.
This means that all automated messages will appear as though they came from the owner, not the co-host.
The only other option is to connect the listing using the account of the owner of an Airbnb Team that the listing has been shared with.