You're able to have more than one Contact for a Billing name, and can easily add other Contacts for the same company/group if required. This can be done in the Web Portal and in the App. In the Web Portal you can add a new Contact to a Billing name from either the Contacts list view, or the Contact Card view.
To add from the Contacts list view, go to CRM > Contacts > Select the Contact name > Contacts tab > + symbol.
To add a new person through the full contact card go to CRM > Contacts > Select the Contact ID number or Arrow (this takes you to the full contact card page) > Contacts tab > + symbol and add the new contact. Remember to click Save after.
To add a new person to an existing contact in the App > Contacts > Select the contact you would like to add the person to > Select "People" > + symbol at the bottom right of the page to add the New Contact.
This can also be done when creating a new job.