Samsung vs Google Calendar

On my Samsung Galaxy S3, I have two calendar applications : Google Calendar and S Planner (S Calendrier in French). Both applications are able to display all phone calendars :

• My Calendar : To display contact birthdays
• Samsung calendar
• Google calendar(s) : your own Google calendar(s) and your contacts'

If you sync these calendars, this will only keep in sync your phone calendars with the various clouds (Google, Samsung, Facebook, etc.). But this will not sync calendars between one another.
Sometimes, Samsung Calendar becomes the default when you create new events. I have seen lots of people on the web looking for ways to import/export from Samsung Calendar to Google, or to sync them...
Once an event is created, AFAIK, it is not possible on my phone to move the event to another calendar.
I have found a solution : with Kies Air opened in your computer browse, you can move events to another calendar.
How to proceed :

• (phone) Open Samsung Kies Air app
• (computer) Open Kies Air in your browser : http://phone.ip:8080
• (computer) Enter PIN displayed on your phone
• (computer) Open Calendar and edit events to move them to other calendars

HTH