Can you get an advocate for S2? A social worker who speaks for him and visits both houses? What S2 said to you sounds concerning to me.
My D has things like that all the time but is obsessed with her dad. This evening I had to listen for a long time all about how she realized she met OW SIX YEARS AGO and also in the fall, when my H was still calling her his friend. It is so awful and painful. After I had to run to my church, which is still closed, and pray against the door. I let myself pray for some very dark things to happen to H and OW and then slowly asked for hope and love.
But I digress. My point is that I would not push what S2 said aside.
I believe I will see the bounty of the Lord in the land of the living. Wait for the Lord with courage. Be stouthearted, and wait for the Lord.