1-Go to old "@gmail" Calendar

2-Click on "Settings"

3-Click on "Calendars" tab next to General tab

4-Click "Export Calendars"

5-Save the ".zip" file on your desktop

6-Extract all the files

7-Go to Calendar Settings in new "@synergycompanies" email account

8-Click on "Import Calendar"

9-In the pop-up window under "Browse:" select the file from the extracted files of Calendar1 (Original Gmail Calendar)

10-In the pop-up window, under "Calendar:" select Calendar2 (New Synergy Calendar)

11-In the pop-up window, click "Import"

12-You're done! A calendar importing ~220 events, took ~30 seconds to import according to one website (Based on internet speeds I'm guessing) Once the calendar successfully imports, you can delete Calendar1, since you merged the events into Calendar2. Otherwise just leave Calendar1 (gmail) and all previous events should be copied to Calendar 2 (Synergy)

Hope this helps.

https://productforums.google.com/forum/#!topic/calendar/UrSU2OszNPs