How do I provide a third of my estate to my disabled daughter who is 56 and onSSI from a brain injury?

You should definitely call an attorney who specializes in Estate Law. Simply stated, you would bequeath the 1/3 share of your estate into a trust for your disabled daughter. Tou would then name a Trustee to manage and administer your daughter's Trust, under your Will. In your Will, the Trust would be identified, the Trustee would be named, and the Will would describe the type of Trust and how and when the  money in the Trust would be used or even distributed. The trust provisions in your Will could provide for ongoing payment of rent, medical  expenses. . .