Would we be able to link other companies/persons to our incident?

Example: Hotel City  has a full evacuation and they need help from other General Managers within the corporation in the London area.

If you are part of a corporation, you can always escalate (auto or manual) an incident, thereby triggering an alert in the level above. You can also have a list of managers from your cooperating companies to alert quickly if in need. You can even have them attending your crisis team either as a view only or as a member who is able to participate with own tasks.