Legal Entitlement?

My father died suddenly in April 2007. He left a will which stated that everything was to be shared equally between his 3 children. Myself, my brother and my sister. His estranged wife whom he had been separated from for 9 years made a claim for her "Legal Entitlement". She died a few months after my father in 2007. Her claim is still being persued through her executor. I would like to know if there is any way I can dispute this, and if so how would I go about it? Please advise. Many thanks.