ابن زوجة زوجي السابق يؤذي ابني أثناء زيارته لوالده. ماذا أفعل؟

Thanks for your reply.

As I am not with them, I wouldn't know if the mother's intervention is there or not.

Can you directly file a complaint with the police or do I need open up a case in court?

You can complain directly to the police, but on what basis harm has been done to the child, and the intention of those who made him do so?

Because these questions will be asked by the police.