Change the employee doc name

Hello guys
I want to change the employee doc name(The name which employee data save).
I’m saving the doc by naming series (HR setting - select the Employee Naming By Naming series ).

I am using 3rd naming series
ie, WZ.###
WZC.###
WZT.###

First I am saving the employee with WZT.###(Training period)

Again after 3 months, I want to save the doc with WZC.###
(Contract Period)

Again 3 months I want to save the doc with WZ.###
(Full time)

Now we change the name of the document via rename (Enabled the check box Allow Rename in employee doc)
I would like to change via employee promotion like we can change the employee number in the promotion.

Is there ant way to implement

OR

I am tried to implement it in another way,

In the HR setting select the Employee Naming By Naming series and after saving the document the doc name is set to employee number and updated through employee promotion. It works completely. But after I select the Employee it shows the doc name which refers to employee doc save.

So Is there any way to change the name? (not by rename)

Can we add this to the employee promotion category?

Please Help me with this…