Quest Migration Manager - AD Account migration in Same forest with having Same UPN

We are migrating the accounts from one child domain to another child domain in same forest,

since in source domain these accounts are using one specific DNS suffix in UPN and same, we need to carry out in Destination domain, since both the domains are in same forest so not able to keep the same UPN, we have tried to change the UPN in source just before migration and updated desired UPN in destination after migration in destination, but this is causing the accounts deletion in azure AD. 
we are looking for the solution to migrate the account without deletion in Azure.