to all those who have asked me recently…. I believe this could sove your problems and help you merge your selected calendars:
Go to Google Calendar, Choose any account and click “Calendar settings” from the drop down arrow to the right of the calendar, click HTML from the “Calendar address :“, then choose “use our configuration tool“. Now choose one of the left column “Calendars to Display” and all of the customizations you need. The HTML will auto renew. Then copy and paste the HTML where ever you want it to show…   x kc