Many of our health issues today are thought to occur in large part because our diets are so horribly skewed to omega 6s. Here's a wiki article on GLAhttp://en.wikipedia.org/wiki/Gamma-Linolenic_acid
Personally, I'd stick with a tasty reputable fish oil made for kids and maybe incorporate some freshly ground flax seeds into their diet for ALA (short chain omega 3). Omega 9 I would just get by choosing monosaturated fats rich oils over polyunsaturated whenever I could.
eta: We use Coromega but the is a thread on fish oils on the first page where at least one person raves about Barleans.