You need to explain more. Bottom line is that his current wife (at the time of his death) has certain rights - the extent of those rights depends on a number of factors. See an attorney.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature.
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Steven is correct. To determine what, if anything you and your brother are entitled to, you should talk with an experienced probate attorney.
Three vocabulary words and concepts might be of some help (there are many more that may be applicable to your situation):
1--"Testate" From your question, it appears that your father died "testate." That means having prepared a will. To the extent the will was validly executed, it should generally control how his PROBATE estate transfers to heirs. On the flip side, someone who dies without a valid will is described as dying "intestate." For those estates the applicable state law of intestate succession will apply to determine who is a proper heir and what their proper inheritance share is.
2--The "probate estate" includes ONLY those assets that your father owned in his name only. Any assets that were subject to any kind of beneficiary designation or transfer on death designation ARE NOT part of his probate estate. Likewise, any assets that are owned in "joint tenancy" will not be part of his probate estate, as joint tenancy assets automatically become the property of the surviving co-owner on death.
3--"Spousal Election," this may or may not be the term in New York, but the concept is this--when someone dies and leaves a probate estate, the surviving spouse may have the right to "take" or "elect" their share against the estate, not withstanding the terms of the will.
Disclaimer: My answer is provided without all relevant facts, let alone your unique objectives. No attorney-client relationship is hereby created as a consequence and you should not take (or not take) any action based on my answer. I highly recommend that you consult with competent legal counsel before deciding to take or not take any action, as every situation is more complex than it appears.
I concur with the other attorneys. You haven't provided enough information to provide you with definitive answers. I'm curious how you know the size of the estate.
If his old will he executed is found and proved to be valid by the court then its terms will be followed. However, in North Carolina, a spouse has certain rights and if she files a timely renunciation will take a portion of the estate. Definitely seek experienced counsel to see where things stand and what rights you have.