How is the inheritance divided among the deceased's father, full brother, and full sister?

If the heirs are limited to those mentioned, then only the father inherits because he is the closest 'asabah (agnate), and the sister has no prescribed share (fard) in this case. The matter of estates should be referred to the Sharia courts for investigation, as there may be wills, debts, or other rights that take precedence over the rights of the heirs.