Hi @Necoms · Thank you for reaching out.
You cannot sync users from Azure AD B2C to Azure AD B2B tenant. Best you can do is, bulk invite B2C users as guests in B2B Tenant.
- From B2C tenant use the Download users option and download all users in a csv file.
- In the B2B tenant, use bulk invite option.
- Download the template, copy email addresses from the CSV file in step1 and paste in the template you downloaded.
- Upload the updated template file and submit. This will create guest users in your B2B tenants in bulk and send them invitation email as well. Users will have to redeem the invitation before they can access resources from the B2B tenant.
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