Reactivation of user account

I need to reactivate a user account (which is deactivated in the system as the user has left the organization). There is no formal written procedure on reactivation of a disabled account. The need to do this is that certain business objects are associated with the disabled user account which now needs to be changed/modified.

Can I document this scenario, reactivate the said user account, assign the business objects to admin group and deactivate the user account - all this by taking evidence.

I appreciate any help on this.