Legal Question in Wills and Trusts in North Carolina

You don't post any relevant facts here. I don't know whether your grandparents in fact had a joint and mutual will. Assuming they did, then here is what would happen. When the first person died, the will would be probated and estate distributed. If the second spouse never changed their will and died the joint and mutual will would get probated again and assets distributed as per the will.

The problem with joint and mutual wills is that the surviving spouse is ALWAYS free to make a new will after the other spouse dies. So if that is what happened, the joint and mutual old will is no longer valid as to the surviving spouse.

You ask if its "legal." Anything not prohibited is legal. So unless you have evidence that someone forged a new will on behalf of your grandfather, then its legal. Is it valid? Maybe and maybe not, but you post no facts suggesting any fraud or undue influence or anything else affecting its validity so I cannot say.

Does your grandfather have to abide by the wishes set forth in your grandmother's joint and mutual will? No. He is free to dispose of his assets any way that he sees fit and he is not obligated to leave anything at all to either his children or grandchildren. Its his property. He could have left it all to his favorite charity if he wished and as long as he was of sound mind and there was no fraud/undue influence that would be perfectly valid. So while I understand your disappointment, do not act as though the grandchild had some sort of inviolable rights of inheritance here.

Where you live is NOT relevant. Its where your grandparents lived at the time of their deaths as that is where their estates will be probated. My answers are premised on NC law so I assume that your grandparents lived here as well.

Since you post no real useful information, I suggest that you get a copy of both your grandmother's and grandfather's wills and pay to have it reviewed by a probate lawyer who practices in the county/state where your grandparents each lived at the time of their deaths. You also need to make a list of all children and grandchildren, note whether any of them has died and when and you need to note when the second will was made by your grandfather. Was it recent? Or some years ago? What was his mental condition like at the time? Do you believe the second will was the product of fraud/undue influence by someone? Ask the lawyer if there are grounds for a will caveat and find out what it will cost. Is there any chance that the omission was due to error rather than deliberate? Even if you succeed in a will caveat, its not going to automatically revive your grandmother's will. If your grandfather's will is tossed out, then he will be deemed to have died without a will at all and the 5 children would inherit, but not any grandchild. The grandchildren would only inherit if their parent died and they would inherit their dead parent's share.