Located in the Account details section of the customer profile, just below the Contacts and Customer portal section.

Select the + icon to enter a new Beneficial owner contact

Enter the Owner details.

Select if you want the Beneficial Owner to be associated with a specific location

Will the property owner be included in the emailed Invoice or Payment Receipt?

Not automatically. You can save the Property owner information without enabling email contact. If you want the property owner to receive a copy of the invoice and payment receipt, select the "Associated With: Service Location" option