We have some contacts in our Zoho database that more than two contact owners should have access to. We don't want all our users to be able to edit all of our information in Zoho, which is why we set their user accounts to standard, however for contacts specifically, we'd like to allow more than one user to be able to interact (assign activities, due dates, etc) with that contact, regardless if they are the contact owner or not. 

How do we go about achieving this?

Thanks