This is a suggested list of documents for caregivers and the veterans for whom they care.  Necessary documents will vary by situation.  Review documents any time there is a change in circumstance or at least annually to adjust for changing circumstances, state/federal law changes, etc.

http://www.moaa.org/Caregiver/Legal/Legal-Documents-Checklist/
Documents to be drafted
General Power of Attorney
Durable Power of Attorney
Durable Medical Power of Attorney
Health Insurance Portability and Accountability Act authorization
Living will and/or do-not-resuscitate order (Advanced Medical Directive)
Will and/or trust
Guardianship papers (if applicable to the situation)

Documents to be kept in a safe place
Certified copy of the military medical records
DD Form 214/DD Form 215
Medical Evaluation Board/Physical Evaluation Board or Integrated Disability Evaluation System ratings
VA disability ratings or pension letter
Social Security disability award letter
Declaration of a VA fiduciary
Declaration of Social Security representative payee status
Mortgage/property deeds/rental agreements
Insurance policy papers (auto, home, health care, life)
Vehicle titles/loan papers
Birth certificates
Marriage certificates/divorce decrees
Custodial agreements
Diplomas
Combat-Related Special Compensation award letter
Other documents as needed