As the account owner, you can invite new users to join your wedding planning dashboard!

Go to Settings > Users and you'll see the users who have access to your planning portal.

Press the Invite user button to send an email invitation to your partner, wedding party attendant, or a family member who has offered to help you with your wedding tasks. 

Once a user has accepted your invitation, you'll be able to create and assign tasks to them through your Planner!