How to programmatically setup Azure B2C federated accounts

I have a B2C tenant that is using an Azure AD tenant as an OIDC provider using IEF and a custom policy as described here. When I login to B2C with a user from the federated tenant, it creates a special user in the B2C tenant (username shows name of custom identity provider). Is there a way to programmatically add these federated users to the B2C tenant? That is the desired functionality for my scenario but have been unable to accomplish it using AAD Graph API.