Unfortunately this is what you will have to do, it is simply a limitation of how the systems in the game work. You can have the terminals align even closer (one tile apart is enough) - but that tile may still end up getting trashed and will have to be cleared out by a team not assigned to a terminal.
Yes, that was the solution I eventually worked out
If you have a large number of staff then having an “External Services” staff room with just one Janitor and Service Techinican can cover the entire remaining airport