Does extra vitamin d help with boost a child's absorption of calcium?

If he is deficient: If he has absorption problems or is not getting enough sun exposure or always has sunblock on (which is good, but blocks 95% of vitamin d production). If he does not have a deficiency, then the extra vitamin d will increase calcium above the levels needed. Consistent vitamin d and calcium intake through a lifetime is the way to go. There is such things as too much of a good thing, too!