All contacts created, or any information edited or deleted in the following options on the Action ribbon; will be updated on the Contacts section of the "Calendar" screen:

Contacts

Debtors - Contacts tab  

Creditors - Contacts tab

If any contacts have been deleted in Contacts on the Action ribbon, etc., these contacts will also be removed from this screen. 

calendar-contacts

You may add, edit and or delete contacts in the Calendar.

Reports for contacts can be printed in the following options on the Reports ribbon: 

Reports → Contacts - Lists all contacts for debtors (customers / clients) as well as contacts for creditors (suppliers / vendors).

Reports → Debtors → Listing - Contacts - Lists only contacts for debtors (customers / clients).

Reports → Creditors → Listing - Contacts - Lists only contacts for creditors (suppliers / vendors).