A proxy will that meets the effective conditions prescribed by law is valid. And the above conditions generally include that there must be more than two witnesses present, one of whom can be a documentary representative; The testator shall have full capacity for civil conduct; The agent, witness and testator must sign the will.

First, old people who can't write a will can't post their names.

The will of an old man who cannot sign a letter shall meet the following requirements:

1, the will must express the true meaning of the testator;

2. The testator has full capacity for civil conduct;

3. The content and form of the will shall not violate the law;

4. There should be more than two witnesses present, and one of them will write the book on behalf of the testator, the scrivener and other witnesses, and indicate the year, month and day.

To sum up, it depends on whether writing a will on behalf of others complies with the law. According to the provisions of China's civil code, there should be more than two witnesses present when making a will, and one of them will write the book, indicating the year, month and day, and it will be signed by the person who wrote the book, other witnesses and the testator.

Legal basis:

civil law

Article 135

A will that entrusts others to write on behalf of others shall be witnessed by two or more witnesses, and one of them shall write on behalf of others, which shall be signed by the testator, agent and other witnesses, and marked with the year, month and day.

Article 143

A will made by a person without or with limited capacity for civil conduct is invalid.

A will must express the true meaning of the testator, and a will made by fraud or coercion is invalid.

Forged wills are invalid.

If the will is tampered with, the tampered contents are invalid.