Advice

My grandson has ADHD/AUTISM he is now 7 years old his father would slap him across the face and head for making a mess on the table,he would be made to clean up his vomit,clean the floor if he had urinated on it whilst going to the toilet  or punished for behaviour the father viewed as defiant such as being stupid in his fathers words .

My grandson has been now living with me under a child protection plan he sees his father once ever two weeks which are moderately okay but on videocalls he tells his father he hates him ,he doesn’t want to see him because he was always slapping him.l don’t know what to do as the father is accusing me of coaching my grandson to say these things.My grandson can me fine on the start of the videocalls then suddenly starts shouting liar l hate you and becomes extremely overwhelmed.

would appreciate any advice