Part 4, Items 25-44 of Form I-130, Petition for Alien Relative, requires the petitioner to list the relative's spouse and children.
The Immigration and Naturalization Act (INA) defines children as unmarried sons and daughters under the age of 21 years. Therefore, list all unmarried children under 21 years of age at the time of filing, even if they do not intend to immigrate with the parent.
If they do intend to immigrant with the principal beneficiary (person named in Part 4, Item 4), the spouse and unmarried children under 21 years of age may qualify as derivative beneficiaries. That means that they will be able to apply for a green card at the same time as the principal beneficiary, once the I-130 petition is approved and current. A separate I-130 is not required for the derivative beneficiaries.
Step children of U.S. citizens do not qualify as derivative beneficiaries. A separate I-130 petition must be filed for any individual that qualifies as an immediate relative.