You can now connect your Amazon store to the Marketplace Manager even if you only have a "child account".
Just make sure that your "child account" has the View & Edit permissions set for the Marketplace Appstore functionality inside Amazon Seller Central.
Here's an example of how your permissions should look like:
If you don't have the View & Edit permissions for the Marketplace Appstore, reach out to someone who has access to the Master account so they can set this permission for you.
If you need any help just say hi in chat, or book time with us here. We’ll set up a screen share and do it with you.
If you have any other questions, just let us know. We're always happy to help!