I assume this is what you are referring to:
Fla. Stat. 732.401 Descent of homestead.--
(1) If not devised as permitted by law and the Florida Constitution, the homestead shall descend in the same manner as other intestate property; but if the decedent is survived by a spouse and lineal descendants, the surviving spouse shall take a life estate in the homestead, with a vested remainder to the lineal descendants in being at the time of the decedent's death per stirpes.
(2) Subsection (1) shall not apply to property that the decedent and the surviving spouse owned as tenants by the entirety.
732.4015 Devise of homestead.--
(1) As provided by the Florida Constitution, the homestead shall not be subject to devise if the owner is survived by a spouse or minor child, except that the homestead may be devised to the owner's spouse if there is no minor child.
(2) For the purposes of subsection (1), the term:
(a) "Owner" includes the grantor of a trust described in s. 733.707(3) that is evidenced by a written instrument which is in existence at the time of the grantor's death as if the interest held in trust was owned by the grantor.
(b) "Devise" includes a disposition by trust of that portion of the trust estate which, if titled in the name of the grantor of the trust, would be the grantor's homestead.
As far as a percentage, I don't see how the attorney gets 20% out of 3 siblings. The widow should get 100% and when she dies, the siblings slit the estate equally...