How I can add an application to my Entra External ID user flow using Graph API?

Context

We have built a portal where our in-house developers can register their applications. After approval, graph API's are called automatically to create the app registration/service principal.

Multiple forms of authentication are supported.

Use case

We want to extend the OAuth authentication service registration to allow users to add "self-service sign-up" functionality to their applications.

While we can manually add the application to the "self-service sign-up" feature:

Microsoft Documentation on Self-Service Sign-Up User Flow

We would like to automate this process.

Problem

There is plenty of documentation describing how to configure identity providers for the user flow.

However, I have not found any documentation regarding "adding an application to this user flows".

Research
I already examined the call made by the Entra portal. It seems to connect to:

https://cpim.windows.net/graph/$metadata#susiConfigPolicies

FYI: CPIM stands for: Customer and Partner Identity Management. MS uses this name on the inside to refer to AAD B2C.

source: https://stackoverflow.com/questions/72881808/what-does-cpim-stand-for-in-the-context-of-aad-b2c

With the following payload:

{  

  "applicationId": "",  

  "userFlowId": ""  

}

Question

Could you please provide me with a link to documentation how I can add an application to my user flow using Graph API?

Thank you in advance!

Best regards,

Danny