How can I assign two or more companies to a person?
If you want to assign more than one company to a person, either because that person previously worked for another company, or because it currently works for different companies, go to the appropriate person and select “Edit Person” on the right.
In the line "Position", you can find the option "Add additional position" below in gray. In the field that opens any number of other companies, the position of the person or the department can be added.
When the person has changed the company, it makes more sense to put the previous company on the former than simply overwrite the company. This keeps the history complete. For the second company, the checkbox at the main item can be clicked.