how to create an ad-b2c tenant under existing subscription

Question

I am trying out ad-b2c and boy even the first step is turning out to be extremely frustrating. Anyway here's my problem:

1. I have an existing subscription with a default directory which has its own mydefaultdirectory.onmicrosoft.com domain
2. According to instructions here: I should be able to create an ad-b2c tenant, and then go into the portal B2C features blade.
3. I created the tenant, which included me creating a custom ad-b2c directory. I had to choose another domain such as myadb2ctest.onmicrosoft.com.
4. I go to the portal under b2c blade, but now I have no subscription. This is because now I am logged in to the myadb2ctest directory rather than mydefaultdirectory which has my subscription.
5. I DO NOT want to create a new subscription. I just want this directory associated with my already existing subscription so I can try this thing out.

Answer 1

An Azure AD (and B2C) is a higher level object than a subscription in the portal user interface. That's why you lose your subscription view when selecting B2C.

Internally this will be linked to your subscription, otherwise Microsoft couldn't send you a bill. if you go to the B2C dashboard, there is text containing the linked subscription:

Subscription status

If there is no subscription linked, there is a warning in the B2C Dashboard:

No Subscription linked to this B2C tenant or the Subscription needs your attention.

And then you will need to take these actions:

This B2C tenant must be linked to an active Azure subscription for communication, support and billing.

If your Subscription status is No Subscription, please link this B2C tenant to an Azure subscription,

1. Switch Directories to the location of your target Azure subscription
2. Under Marketplace, search for and select 'B2C'
3. Select Create to link this B2C Tenant to a subscription

Answer 2

Unfortunately today B2C features cannot be turned on in an existing tenant.

https://learn.microsoft.com/en-us/azure/active-directory-b2c/active-directory-b2c-faqs

Answer 3

Please make your B2C directory a default directory for an Azure Subscription. You could think of a B2C directory as a normal AAD during this process.

This process of switching the default directory can only be done through Azure Classic Portal using Service Admin (live account ONLY) for the subscription.

You could refer this article for further steps: https://ballance.in/default-directory-of-an-azure-subscription/