Estate planning can be very complicated, especially when planning for the care of a disabled individual. An attorney experienced in estate planning can help you foresee what issues may arise and help plan to avoid those problems.
What is so wrong with DIY online wills? There are just so many things that can go wrong--misplace a decimal point, forget about that antique jewelry box, or not have enough witnesses at signing-- and your estate plan could be deemed invalid. Are you willing to take that chance with your legacy?