When I received my SSDI award it was a lessor amount because my adult autistic son collects SSI from my SS benefits. Example: Awarded $2800 but $600 was deducted for my son's SSI payments. I was just told he should of applied for benefits under his father and he would probably receive a larger amount & I would not have the $600 deducted from my ssdi. Since he's been collecting long before I, shouldnt my SSDI not only increase the award to $2800 but also go retroactive with the $600 they've dinged me for my son's SSI? Why wasnt this automatic? All my paper work show I am a single dad with an autistic son that is on SSI...??