There are two ways to open the Customer contacts form:
If you access the form using this method, you will see all the contacts that are registered for all of your customers. The main advantage of this method is that you can create various overviews and selections of your contacts, regardless of the customer they work for. For instance, you could group all contacts with the position of 'Purchase employee' and send them a particular offer.
It is not possible to add contacts when you have accessed the form in this way.
If you open the Customer contacts form using this method, you will only see the contacts registered with the customer you selected when you clicked the Contacts button.
If you have accessed the form in this way, you can add contacts.