Wow. You definitely incorporate the lyrical aspect of a lullaby that makes everyone (including myself) want to say "awwwwww...how sweeet." Your lullaby does an excellent job at painting a picture for the audience; very touching indeed. I also like how the lullaby begins to fade away starting at measure 27 all the way to the end. Now, if I may, I have a couple ideas for you. I think this lovely lullaby should start incredibly soft, and grow slightly as more layers come in; in particular, there could be small crescendos at every 4 measures until the melody comes in at measure 17. Next, the at measure 24, just after the melody disappears, the celesta could join the in with the piano (treble staff) for the next 4 measures. And finally, at the last measure of the piece, the celesta could play a chord (perticularly, the tonic chord, C-E-G) instead of a single note. I really like what you've done and I hope your cousin likes it too :D