The doctor's statement is the only documentation you need in this case and not the letter from SSDI to take the exemption from the IRS 10% penalty for early withdraw. As you know the amount you received from the distribution is still subject to ordinary income rules. The doctor's statement needs to be concise in it's wording. I would suggest, "that the physical or mental impairment is continuous and of long and indefinite duration". I hope that this helps you and I'm sorry for the disability illness in your family.
