Yummygran there's already been lots of helpful advice on here, so I would just add....if you decide to tell them to sort things out and say how upset you have been by their behaviour, make yourself unavailable when the phone starts ringing, so they can't keep coming back to you to mediate. I had a similar, less dramatic problem with my equally volatile son and daughter a month or so ago. One needed information from the other and I voted with my feet and disappeared off the scene for the afternoon, ignoring phone calls. By the evening they'd had to speak to each other and were friends again.
JaneMarie this is common behaviour and I know of older children who can't be left alone with the new baby. My twin 3 year old grandsons have announced they are planning to 'pow!' their tiny twin girl cousins when they see them, so they will be trussed up and placed in a corner if they aren't careful! (only kidding, but you know what I mean). Most young children don't always realise that they are hurting babies, and other do want to hurt them because they are understandably jealous. It'll pass x
Shall we reboot our cartoons thread again? 😁