Can I notify the Co-owner when a Case violates the SLA?

Yes, you can configure the SLA policy to send email notifications to the Co-owner when a Case is violated. 
Follow these steps to notify the Co-owner when a case violates the SLA:

1. Log in to your CRM account.
2. Click the User Menu in the top right corner. 
3. Click Settings. The Settings page opens.
4. Go to Support.
5. Click SLA Policies. The SLA Policies page opens. 
6. Edit the SLA policy added for the Cases module. 
7. Go to Configure SLA Alerts section. 
8. Add the Co-owner in the Users field.
9. Click Save.