Not simply anyone may challenge the credibility of a Will. State laws vary somewhat, all need that you be related to the Will in some manner. Generally, you need to be able to reveal that you would have received more from the decedent, if she or he had died without a Will; or if he or she wrote an earlier Will that left you more than the current Will.
Question 2: When can I challenge the Will?
Question 3: How can I overturn a Will?