@Luke Lim Thanks for reaching out and apologies for delay on this.
Few things that you can perform to achieve is using the sync rules as mentioned in : https://learn.microsoft.com/en-us/azure/active-directory/hybrid/concept-azure-ad-connect-sync-user-and-contacts
Important thing to note is :
If you have a topology where users are represented as contacts, make sure you select to match users on the mail attribute in the installation guide.
If you select another option, then you will have an order-dependent configuration.
Contact objects will always join on the mail attribute, but user objects will only join on the mail attribute if this option was selected in the installation guide.
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