Question about Samba:

Dear Sir or Madam:

I have the following to ask you related to Samba written script.The questions are like the following:
How to write a script to automatically
1) add a Samba user when a Unix user is added
2) change the Samba user when a Unixuser is changed
3) delete the Samba user when a Unix user is deleted
Thank you so much for your assistance.