You've received great advice above. Apply for both kids. I'll just add that if a child is not accepted into the DYS program at this time, you may reapply at a future date. A child is not limited to one application in a lifetime.

Here's more from the Davidson DYS webpages:
Originally Posted by YS Qualification Criteria webpage
Information included here will not add substantially to the review committee’s decision, nor override test scores that fall significantly below the Minimum Score Guidelines listed above.
This would seem to indicate that scores just missing the cutoff (and within the standard error's confidence interval to include the cutoff score for eligibility) may be considered, depending upon the strength of other portions of the application...

also

Extenuating circumstances, as determined by the applicant and family...