User name change following marriage

Folks,

Im wondering what the correct process is to update a users last name following marriage.

Currently we are:

- Entering employee record and updating last name and email address

- Entering user record and updating user name and linking amended employee record

Problem:

User no longer receives workflow notifications

Can this kind of update be done through forms? or should we be using HR_PERSON_API even for changing just one user?

We are on Oracle E-Business Suites 12.1.3 with an 11g dB

Thanks

Gavin