Hello,
We could not have multiple UPN for one user in AAD. If a user is synced from multiple on-prem then it would be showed as a different user, example:
User 1@jaswant .com and 1@xyz .com will show-up as 2 different users with respective UPN. For topologies supported by AAD kindly refer https://learn.microsoft.com/en-us/azure/active-directory/hybrid/plan-connect-topologies#multiple-forests-single-sync-server-users-are-represented-in-only-one-directory.
Apart from the if you are trying to have multiple independent Azure AD under single corporation then they would be created as a different directories. No user could use the features of outside there respective directory. If you want them to use the features of other directory then user must be created as a guest B2B account in other directory as well, ref: https://learn.microsoft.com/en-us/azure/active-directory/external-identities/external-collaboration-settings-configure
Could be please elaborate on the third question on "is it possible to consolidate payment into one wallet?" how is this related to Azure AD ?
Thanks,
Akshay Kaushik
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