Manage multiple Amazon accounts with one main account/credential

Our technology mirrors Amazon Advertising Console's permissions. You need to gather all your accounts into one main account.

Each m19 user is linked to an account ID and to an Amazon user ID. The best way to gather all your accounts is to grant each account access to one main account. For each account you manage, you need to log as an administrator and grant access to your main account by following the tutorial for Vendors or for Sellers.

Once done, you should see all your accounts on M19 by logging in with your main accounts. If one of your accounts is not available from your main account afterward, please check that :

The account advertising is activated. The marketplace should contain one created campaign at least.
The marketplace has no credit card issue
You can create or pause a campaign in the Advertising console
You can create or pause an ad group in the Advertising console
The marketplace is available from M19's setting page
You tried to log in by using the button "Login with Amazon"

Vocabulary

Credentials: An ID and password you use to log in to access one or multiple accounts.
Administrator: The credentials that have access to an account as an admin. Only the administrator can grant access to a secondary user. An administrator is always linked to one or multiple accounts. There is only one administrator for a given account.
Secondary user: All non-administrator credentials for an account
Main account: The credentials you would like to gather all your accounts into!

Quick example

Imagine you manage 3 accounts as an administrator: Apple (vendor), Samsung (seller), and Microsoft (seller). You have 3 credentials, one for each account. As you spend more time on Microsoft, you would like to be able to access Apple and Samsung campaigns without logging out from Microsoft. You need to :

Your Microsoft credentials are your main account, the administrator account of Microsoft, and the secondary user of Apple and Samsung.