Hello PPC P,
Yes, you would have to create a so called MCA (multi-client) for merchant center, which is the equivalent of the MCC account in AdWords. You can read more about the MCA here or apply for one directly here.
When your MCA has been approved by Google you can then add your clients' accounts in your account. In the first link above you can read more about how the rules apply for sub-accounts.
Don't forget to read to policy of Multi accounts, there are restrictions such as you can't have clients with the same products as that will make both or one of your clients get suspended.
The best option is to register a new google account and simply add yourself as a user.
MCC is not currently designed for agencies.
Did you find any helpful responses or answers to your query? If yes, please click on ‘Accept As Solution’