I am an Estate Probate Wills and Trust litigator lawyer.  We are often involed in Will Contests, Will Challenges, and Trust Disputes including "Busting" or "Breaking" Trusts.     We handle large disputes around the state.  

You can dispute a Will when typically on followig grounds:

• Fraud - deceived the testaor 
• Forgery - if the Will is altered or signatrue is forged
• Undue influece - When someoen is made to do sometthing they woud not otherise do
• Diminished Capcity - if the testator is seneile or heavily medicateed and somenone was taken advantage of by others
• Lacking capacity - if someone has dementia or has other cogntive issues that would impair their ability to do a Will, similair to ability to make a contract.