Do not talk to parent or grandparents. You do not know how they. Will respond.
Is the preschool part of the public school system? If it is the preschool can ask for help from the district. The parent/grandparents have more resources.
If the school is private, the parent/grandparent can ask that he be evaluated by a program used by the district. Federal law requires that schools evaluate so that the child will succeed in school. I suggest the school director can call them to ask what services they provide. The district office will have their number.
My grandson was angry and hit people and was unable to follow directions
My daughter asked for an evaluation. The district placed him in a therapeutic preschool. He was 3.
I wonder if the director and grandparents know this.
If someone calls CPS, they may be able to get involved. Emphasis on may. It's.possible their office is already involved. You mentioned the possibility the grandparents seem to be the ones who have the responsibility of his care. The mom is young and lives with them. Just a possibility. If CPS is involved the school may know this but would not be able to tell you.
Perhaps knowing this information will help you when you talk with the director.
I agree thst.if the school is unable to protect your son it's time to change schools. I also agree that you keep a record and also call the director or the head teacher each time it happens.
I also suggest that protecting him takes precedent over the continuity that staying provides. He will be in a different setting with different kids when he starts kindergarten. Consider that changing schools gives both you and your son experience that may make starting kindergarten less difficult.