1) According to the leave rules of addl. post, when the post will be permanent ,then you may enjoy your ML.
2) After retention/Permanent you will enjoy your M.L. Your previous M.L. will deposit in your Service Book as usual .
3) In case of promotion i.e. Clerk to Asst. Teacher or Asst. Teacher to H.M., your probation period may be relaxed for one year in your new place after considering by MC.
Thanks a lot.