A valid deed prevails over the provisions in a will. Your aunt could not validly transfer the real property after your grandfather died. You need to see an attorney about this issue.
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A valid deed is stronger than the provisions in a will upon death.
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.
You need to do a title search to determine how title was held before grandfather's death and how it was changed after. A will only affects the passage of title held in an individuals name at death. If held in joint tenancy, the deed would control not the will. That said, deeds can be challenged for all the reasons of a contract or Will. There may be statutes of limitations running so you need to consult an attorney immediately.
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Technically you are in the weak position.....however given that the will seems to reflect an equal division of the decedent's properties equally to the 2 daughters then it begs the question why grandpa did not change the deed to conform to his wishes. Lack of understanding and the advice of the attorney who drafted the wills knowing what grandpa wanted vs. What the deeds say are factual issues whereby you may able to establish a suit to force the aunt into settling....you have to get a probate attorney as this will be expensive and not a guaranteed winner at the end of the day.
My answer is not intended to be giving legal advice and this topic can be a complex area where the advice of a licensed attorney in your State should be obtained.
You can go to the recorder's website and check title on the property. If the aunt held the property in joint tenancy with her dad, then she could have transferred title to her following his death by submitting an Affidavit of Death of Joint Tenant. Otherwise, she could not have transferred title. If your husband's mom is the named executor, she should meet with an attorney familiar with probate.
A valid deed will control over a will provision. One cannot assign interest in property that one does not own upon their death.