First of all, according to the relevant provisions of the Civil Code, notarized wills no longer have priority, so whether the will is notarized or not does not affect the validity of the will.

Secondly, what kind of will did Grandpa make? If you write your own will, you only need grandpa to write it himself, indicating the year, month and day, without witnesses. If it is other types, such as writing wills, printing wills, etc. Two witnesses are needed. One witness is not enough. If grandpa's will is not written by himself and only one witness is present, it may be invalid because it does not meet the statutory formal requirements. Of course, if grandpa's other heirs have no objection to the arrangement of the will, the granddaughter can generally inherit the property according to the will.

In addition, besides the formal requirements, the content of the will also requires that the content is true and legal, which is the true meaning of the testator, and there is no reason for the will to be invalid.

The validity of a will needs to be determined case by case according to the actual situation. If there is a dispute between heirs, it may also involve inheritance litigation. It is suggested that you can entrust or consult a professional lawyer to make a judgment. If necessary, further consultation is welcome.

Relevant laws and regulations:

In Article 134 of the Civil Code, a self-written will is written and signed by the testator, indicating the year, month and day.

Article 135 A will written by an agent shall be witnessed by two or more witnesses, one of whom shall write on behalf of the testator, agent and other witnesses, and shall be signed by the testator, agent and other witnesses, indicating the year, month and day.

Article 136 A printed will shall be witnessed by two or more witnesses. The testator and the witness shall sign on each page of the will and indicate the year, month and day.

Article 137 If a will is made in the form of audio and video recording, two or more witnesses shall be present to witness it. The testator and the witness shall record their names or portraits, as well as the year, month and day by audio and video recording.

Article 138 A testator may make an oral will in an emergency. An oral will shall be witnessed by two or more witnesses. After the emergency is eliminated, if the testator can make a will in writing or in the form of audio and video recording, the oral will made is invalid.

Article 139 A notarized will shall be handled by the testator through a notarization institution.

Article 140 The following persons cannot be witnesses to a will:

(1) Persons without civil capacity, persons with limited civil capacity and other persons without witness capacity;

(2) Heirs and legatees;

(3) People who have an interest in the heirs and legatees.