Getting raw scores for IQ tests

I have a sample of adolescents who were given different IQ tests, the WISC-IV (if they were 16 yrs or under) and the WAIS-IV (if they were over 16 years of age). So I have scaled scores for all of these adolescents, but since they were given different tests, I cannot compare them on their raw scores. Does anyone have any idea how I could derive raw scores for these kids, even though they were given different tests? I want to have comparable raw scores for all of these kids, not the age-corrected scaled scores. I have IQ scaled scores and age data for all of these kids. These particular tests are based on the same theoretical constructs, but of course have different individual items. Any suggestions would be appreciated. Thanks, Maggie

let some kids do both tests