Well, if you want the step, stop, step, stop thing, to cease, then just turn the frequency to max. Which is like 5 or something, I don't remember, just at whatever the highest is. You can turn down the speed. If you want. Turn off stepping animation too. That way if they do stop moving at some point because you wanted them to, then they won't keep walking in place. It'll look normal if you just keep the frequency at max.
Now as for running in circles, this is where you should start using diagonal movements. Do like, 2 right, 1 up-right, 2 up, 1 up-left, 2 left, 1 down-left, 2 down, 1 down-right, and repeat. That's a fairly small circle but it's a circle. You can make it bigger and what-not. Do what you think looks best.
Just an idea though. If there's like a stump around this grassy area, you could have the little girl or kid or whoever run in circles a few times, then occasionally stop behind the stump, then have the other kid or kids pause then turn at the stump then run to it and have the little girl or kid or whoever do a little jump, then the sequence continues running in circles.