When my son was 4 he decided he needed to make a quilt for his build a bear!! I was petrified!!! To say the least. He sat on my lap and I helped him guide the fabric making sure no little fingers got in the way. He was sooo proud, we still have it with his bear in the attic.
Maybe for Christmas you could get him a childs sewing machine. Wouldn't he love that, his own!!
By the way, your dgs is a cutie!!