Can Modifying Email (Email mapped with DN - in FIM Sync) will link with user that is already provisioned to external system(Google)

Hi,

 We have provisioned users from FIM to Google(used Generic REST API MA) by mapping "Email" with "DN". Now we need to change that Email at FIM.We want to link the changed Email with the user present in Google.But when we do an export it is creating a new user at Google because of new DN.How we can modify the DN in FIM Sync Provision Code so that the new DN(Email) will be updated to the already existing user at Google.

Please suggest me.

Thanks

Prasanthi.