And pain is a subjective complaint, so pain alone does not warrant disability. If there are no objective medical findings to support the pain complaints, disability is a moot point.Perhaps you do, but your experience is still not the same as anyone else's.
Pain is a symptom, rarely a diagnosis.
Regardless, back to the OP
1) what exactly does the settlement from Work Comp say?
2) has the family member been treating w/ a doctor since the settlement, and who has paid for said treatment? Was he diagnosed w/ sciatica as a result of the injury? How was he diagnosed w/ sciatica?
3) How long has he not been able to work? And how has he supported himself?