- Link the client accounts to your My Client Center (MCC) manager account
- Consolidate the 3 accounts into a new AdWords account you create
- Pause your clients’ campaigns and recreate them in your manager acccount
- Use your clients’ sign-in information to access and manage the accounts
Explanation: If you’re an agency or someone who manages multiple AdWords accounts, a manager account is a powerful tool that could save you time. A manager account is an AdWords account that lets you easily view and manage multiple AdWords accounts — including other manager accounts — from a single location.
Read more here: https://support.google.com/partners/answer/6139186?hl=en