The way that you children could make a claim for more of the estate than your husband's mother's current will leaves them is to prove that the mother was incompetent at the time she revised her will, was forced into revising her will or that the children stole assets from her, particularly while acting as her power of attorney.
To challenge the will the children would need to file a will caveat. This is done through the probate
court in the county where the estate is filed.
Only the executor of the estate has the authority to sue the children for any assets stolen from the mother. For the children to force this they have to file with the probate court to remove the executor then the new executor can sue the children for the assets.
Not to be discouraging but these suits are complex and expensive. They may find an attorney that will take this case on a contingency basis and only get paid if they win the case. They can search for a local attorney at www.lawyers.com and type in the location and estate litigation.
I cannot provide you with legal advise. I have provided you with information about the law related to your question. My answer, and any information that you find online, should not take the place of having a consultation with a lawyer in your area to advise you regarding your specific issues.
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