To give accesses to the owners, go to Settings in your administrator area and then go to Team:
Here, you will find the list of users currently associated with your account. Click on Add a member to the team, a window will open containing the user creation form. Choose "limited access":
You can choose the tabs you want this user to access, it can be the see and edit inventory, see and edit calendar and see reservations.
Finally, choose the accommodations this user can see.
An email will be sent to the email address provided where the password will be informed.