She's been a substitute for teachers on child birth leave for the last three years, taking over the whole class full time, but paid as a substitute. She was told she would be taking over a class as a teacher resigned and moved to full time (regular teacher status). Now that was amended to so that she is full time "probationary" which is called interim here IIUC.

Now the good news- I picked up my sons from school just a few minutes ago and the son in question had a conference with the Principal and he was told he would be moved back to fourth grade (note my spelling was wrong on several occasions in the letter, lol) very soon with one fifth grade class: science, which is his favorite class intellectually. I nearly dropped the letter off at the office when I was to pick up the boys but decided to wait a day to see what you and others here had to say, and to hear my wife's concerns.

thank you everyone for your help and responses.
William