My two DCs are 9 (Dd) and 7 (ds). They have always fought, but recently it has become intolerable (for me!?!), and I'm not sure if there's a reason or is this just another phase.
They hit each other, say things like I wish you were dead, stand really near and mock each other and are generally really horrid. Often it all ends in tears, with me taking one of them and putting them in another room to separate/ punish/ calm them down.
Has anyone got similar experience? What have you done to diffuse the situation short and long term?