Here is something I did to help resolve harsh words and frustration between the sibs when they were tweens/ pre-teens 9 & 13
I enlarged a picture of them a headshot. I mounted in on cork board. Every time they were mean or hurtful to their sibling they had to go stick a push pin in their siblings face. This lasted for about 3 weeks. The pictures were riddled with holes and they didn't like it at all.
At the end I sat them down, and I asked them to remove every pin and say, I'm sorry. They did. Then I peeled of their photograph and behind each was a photo of Jesus' face, now riddled with holes as well.
They burst into tears.
It was very powerful and I am sure this might be too much for some children. Know your kids and whether this would be impacting. It was a major turning point for us in our daily lives.
Sayings I had around the house.
Cradle to Grave -brothers and sisters are your best friends
Goal: Get to Heaven, Bring your Brother