A more thorough explanation:

An accompanying relative, also known as an immediate relative, is a family member of a person who has immigrated to the United States. This family member is eligible for Visa applications and/or Green Card. They are usually the children of an immigrant who have not reached the age of majority or unmarried spouses of an individual who has immigrated to the United States.

For example, if a person immigrates to the United States and has a child who is under 21 years old, that child is considered an accompanying relative. Similarly, if a person immigrates to the United States and has an unmarried spouse, that spouse is also considered an accompanying relative.

It is important to note that an accompanying relative cannot precede the principal visa holder into the United States. This means that they cannot enter the United States before the person they are accompanying. If they do, their admission to the United States will be procedurally defective.

For instance, in the case of Turfah v. United States Citizenship & Immigration Services 2016, the petitioner entered the United States twenty-four days before his father, who was the principal visa holder. As a result, the petitioner's admission to the United States was procedurally defective.

In conclusion, an accompanying relative is a family member of a person who has immigrated to the United States and is eligible for Visa applications and/or Green Card. However, they cannot enter the United States before the person they are accompanying.