It makes a big difference because the support rule is different for a Qualifying Child (QC) vs. a QualifyingRelative (QR).
For a QC the key question is: is she supporting herself. For a QR the key question is: are you (the taxpayer who wants to claim her) supporting her. Since you have established that you do not provide more than half her support, she cannot be your QR. So now we look at can she be your QC. And that depends on whether she provides more than half her own support and that depends on whether that SSI is her money or state (third party) money.
