Contacts working for multiple companies

This is always a tricky problem your idea of using an individual maybe helpful. I would suggest that you could link the individual to several different organisations using the related entries feature. This is not perfect as you will not see the contact immediately amongst the other people at the company but does allow the person to only exist in the database once and be connected to their related employers.

To relate the individual simply drag the individual onto the employing companies record in the address book window and choose relate.

I suggest you tick the box that says relate in both directions and use a relationship description such as "employer/employee"