Sorry hon, bad news, it's all downhill from here!
Only joking, but apparently they all do it. First the arms, then the eyes/head move around to look at any noise, then the legs start. Ds is practically Riverdancing some days! I don't think there is much you can do. Have you got a boppy or comfy cushions? I found it improved slightly when his whole body was supported (he's very long). I even tried swaddling once, but that just made him cross!
BTW I saw you other post about pacis. I think the advice is to replace about once a month, so if you've got 3 @ 3 months old, I'd think they're about due for a replace.
HTH
Caroline