Hi @Mike
Thanks for reaching out.
When you invite a B2C user to your B2B tenant, the user will receive an invitation email with a link to redeem the invitation. By default, the user will need to retrieve a one-time passcode from their email to complete the sign-in process. However, you can change this behavior by disabling the "Email One Time passcode for guests" feature for B2B guest users in your Azure AD tenant.
Disabling this option promoted users to create a Microsoft account for local users created in B2C.
Reference -https://learn.microsoft.com/en-us/azure/active-directory/external-identities/one-time-passcode
Hope this will help.
Thanks,
Shweta
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