Some people are ostriches. My husband is one. If he pretends everything is ok, maybe it will be. He will not involve himself in drama.
If the father hasn’t asked about the “incident” in 10 months, assume that he’s hoping it will go away. It may, it may not.
Everyone gets to deal with situations the way they want to. That includes the father, the sil and the wife.
But maybe the @gpo613 and his wife are happy with this season of life. When they want to deal with it or interact with the sil and bil, they will. On their timetable.
Families are so complicated, aren’t they?