When Google finally decided to kill off the BlackBerry Google Sync app, I wasn't a happy camper. For as long as I can remember I've kept no less than five calendars tied to my main Gmail account, so not being able to sync them on my BlackBerry was a heartbreak for me. I searched and searched for a way to keep them all going on my Bold 9900 to no avail. The only way to do the job was a painful addition of each account to my device, and things just got messy at that point. Thankfully BlackBerry 10 brings both Exchange ActiveSync and CalDAV support, so with a few tricks you can get in sync with all of your Google calendars on your BlackBerry Z10 or BlackBerry Q10.
HOW TO SYNC MULTIPLE GOOGLE CALENDARS
One thing to note here is that Google has pulled ActiveSync for new accounts, so if you don't already have an account you use, this process most likely won't help you at all (but it's worth a shot)
This tutorial is for those who have multiple Google calendars (shared or public) attached to one Google account. If your calendars are on separate accounts, you can either use ActiveSync or CalDAV and just set them up individually. Also keep in mind that this is the way we found works best to get this done. We did extensive trial and error and found this route to be the best option -- sure, it will cost you two bucks, but in the end it's money well spent.
To get started syncing multiple Google calendars to your BlackBerry Z10 or BlackBerry Q10, setup your calendar using Microsoft Exchange ActiveSync on your device. To do this, follow the steps outlined here and be sure to choose Microsoft Exchange ActiveSync (under advanced options). We've tried this method using CalDAV but haven't had much luck, so if you do get things working by that method be sure to drop a comment letting us know what you did.
Once your account is added, grab Calendar Sync ($1.99) from BlackBerry World. This little gem is the ticket to getting multiple calendars. It works in the same manner as choosing what calendars to sync on iOS devices but lets you choose your device and what to sync. So if you only want a certain few or all of them, you can choose to do that here. Also note that you can install this on either your BB10 device or BlackBerry PlayBook, and as long as you've synched up your calendars before, they'll show on either device.
USING CALENDAR SYNC
When you open Calendar Sync, you'll have to login to your Google account.
Next you'll see a screen listing your devices. If you don't see your device listed here (BlackBerry), then select Show All Devices.
This screen will show all devices that have been synched with your Google account, including BlackBerry, PlayBook, iPhone, iPad etc. Choose BlackBerry (it should be the one on top of the list).
The next screen shows all of your available calendars. The toggles should be blank at first -- to sync the calendar, toggle the button so it reads Synced.
When you're done simply exit the app.
Now wait a few minutes (or reboot if you feel like it) and your calendars will shown in the calendar app on your BlackBerry 10 device. You can double check by swiping down from the top bezel when in the calendar, then choosing Manage. Your calendars should now all be listed here and you're good to go!