I had that kind of help too from my daughter. Its the best. When I only had one color for her to work with, she lost enthusiam quickly, but when she got to do murals she had much more fun. She did murals on the inside of mine, but from the looks of your photo, she is a little bit older than your grandson. She is 8.
Kids are wonderful and such a blessing! They are so thrilled to be around and help with the chickens. It is a shame they have to grow up.
HaHa - wish that would work ..DH works out of town most of the time and simply wants no part of my "projects" when he does get home. Built an awesome run though .... guess he thought we were finished.