In the details tab you can add more details to the company. The fields will save automatically when you click off of them. None of the fields are mandatory.
you can add parent companies by clicking on the grey field next to the parent company title and selecting a company from the drop down list. You can do the same for main and editorial agents or you can click the button to add a new one. This will bring up a new window and allow you to create a new agent. Click the button to save them to the company.
You can also add an Invoice company by clicking on the grey area and then selecting the company from the drop down list or adding a new one with the button.