I should add that you can guide the people writing recommendations a bit, by asking them to write about certain things they've told you in the past that might slip their minds. E.g., if the teacher at some point told you "wow, your DS did this most amazing thing and i've never seen kids this age do that." Or "you won't believe what your DD said about this." Refresh their memories! You can also ask them to try to write about anything showing that your kiddo is 2+ years ahead of their agemates.