Changing username(identity) in IdM when infotype 0105 system id changes

Hi All

Please could you provide me some advise on how to address this requirement.

IDM 7.2 SP6

When HR hires a contractor in SAP HR they set the system id in infotype 105 with a specific value eg. X123456. The extract job

creates the identity in IDM with this system id.

In due course if the contractor becomes a permanent employee the system id in 105 is updated to a different value eg. Y123456 by the HR team.

When this occurs and the HR extract job is run as a delta for the same employee nothing happens. The customer expectation is that it would update the identity in IdM with the new system id eg. Y123456 but it fails as the Personnel Number already belongs to a User Account ID in IDM.

Question is, is there a way to meet the customer's expectation? If yes, how?

Are there any drawbacks with this solution?

Please advise

Thanks

Ran