Public Calendars can be managed by multiple admins. You can invite people to become admins via invitation URL links.

1. Tap the three horizontal lines in the top left hand corner of the screen
2. Swipe this menu to the left once to find your public calendars
3. Open your public calendar
4. Select "Options" by tapping on the three dots in the top right hand corner
   
   
   
   
5. Select "Calendar & Member Setting"
   
   
   
   
6. Select Member
   
   
   
   
7. Select "Invite" and share the URL via LINE, Facebook Messenger, Email, Twitter.