My kids have siblings with IQs more than 18 points apart... but they aren't genetically related
Re different schools, it's pretty danged clear to my kids who the EG kid in our family is and who the uber-achieving kid with the HG+ IQ is in our family (and who the non-uber-achieving and MG-at-best IQ is). What we've always tried to do is simply to give each of our children all the opportunities we can to develop all their strengths, and with three kids with three different sets of gifts and three different personalities that at times has meant three different schools and means we spend a lot of time juggling schedules so that they can each participate in the schools and activities that they are interested in. At one point all three were in different schools - and it was great, because all three were in programs they enjoyed and were benefiting from.
In your situation, I'd do just what you're doing - get another test. If you don't *quite* have the scores to get into the school your dd is in, I'd appeal to the school - one point lower than the cutoff is certainly within the standard range of error on the test, and I'd use the sibling argument as reason to possibly suspect the test results (I have a friend who successfully argued this in our school district). Are there other criteria used for program entrance? Does your ds meet those? If it's just one test, one point below the line, that is an issue, I'd guess you could advocate his way into the program!
Best wishes,
polarbear
