More specifically, the physical side of it.
Most times DD is pretty good with DS, but the other day she laid a full on smack on his face/head. I put down DS, said "uh oh" to DD and brought her into her room. I very calmly and without a lot of words told her we need to be gentle with DS and that hitting is not something we do in our house. I let her sit for a couple of minutes in her room after which I gave her a hug and a kiss, brought her out, let her kiss DS and she and I went outdoors.
She's shown a bit more of this physical jealously (or whatever it is) lately and I want to nip it in the bud now. How do you moms of 2+ handle this?