What happens when a will mysteriously appears 9 months after a person's death in Palm beach county?

I filed probate for my father April 2018(he passed away Sept 2017) & was granted letters of administration. I gathered his monetary assets and retained attorneys for civil litigation against two siblings for forging signatures & signing over his two properties to themselves months before he died. Shortly after being served formal notice about a hearing to modify restrictions on the estate, the two siblings produced an alleged last will & testament stating that they are the executors of the estate and more than half of the estate belongs to them & their preferred relatives. This will along with the deeds to the two properties & a POA were all drafted & notarized by a man who claimed to be my father's cpa. My dad's medical records state that he was incapacitated with abnormal range of motion & functional decline. He was kept away from all his other children, friends & family until his death. Before contesting this alleged will, what are the chances of it being voided by the court?