Google Play developer console, how to add an external related project?

Question

I am trying to use the Google Play Developer API to automate APK claims through a service account .

The question is, how do I provide my project (and my service account) OUTSIDE to this game account, API access for managing applications?

Use example and example:

Each of my customers has their own Google Play account, in which their applications live. Applications have always been in one large account, but for many reasons (Google, starting from the highest level), they are now broken.

Suppose you have 2 Google Play accounts, A and B Traditionally, each of these accounts provides the physical email user ( [e-mail] ) “Release Manager” with access to each of their accounts. My email / user address is not on account A and B It works great.

Now I want to automate this process. I go to the developer API console for [e-mail] , turn on the “Android Developer API for Google Play” and create an oAuth2 service account (gives her an email [e-mail] ), Then I tell clients to log in to their accounts ( A and B ) and told them to grant access to the [e-mail] Release Manager.

I make an API call and get

The project ID used to call the Google Play Developer API was not linked in the Google Play Developer Console

API calls work if I log into account A and account B in the Google Play Developer Console> Settings> API Access, as well as service accounts for each. He enters the user account and rights entry for this service user email, and then associates the SINGLE project ID, which MUST be the owner of the Google account.

Questions:

• How to add a service account that is NOT defined in Settings> API Access?
• Why is there only the ability to link 1 project?

You can provide external email addresses with full perms, but you CANNOT provide access to the email API of an external service account? The current design is no more secure. In fact, this seems to run counter to most of the benefits of the API, and also to the fact that Google is struggling to isolate the account.