We find that they do excellently with hands separate; but once we try to put hands together, it requires brain muscle that is not fully developed yet. It's been awesome (and sometimes frustrating) to see (because I tend to get emotionally involved).
Wes denied my suggestion to play a piece that I can't even remember what it was right now. He was determined from the get-go to play Flight of the Bumblebee (Rimsky-Korsakov). Kate is playing Sugar Plum Fairy (Tchaikovsky). And Sophia's is Ode to Joy (Beethoven). Simplified versions, of course.
A few weeks ago Wesley secretly recorded Kate while she was practicing. The result has caused much re-playing of the footage, and laughter all around. I think I laugh more at their reactions than at the recording itself. But I think it warrants documentation here.