The role of unmarried, adult children of lawful permanent residents (LPRs) in the green card process can vary depending on the specific circumstances of the individual case. In general, adult children of LPRs may be eligible to immigrate to the United States through a family-based green card process, but the process and timing can be different than for other family members.
If the adult child is over the age of 21, they will typically be classified as a "second preference" relative, meaning that they are not considered an "immediate relative" and may have to wait longer for a green card to become available. The availability of green cards for second preference relatives is based on a quota system, and the wait time can vary depending on the country of origin and the number of people in line ahead of the individual.
In order to apply for a green card as an adult child of an LPR, the individual will need to first file a petition with U.S. Citizenship and Immigration Services (USCIS) on Form I-130, Petition for Alien Relative. The LPR parent will need to provide proof of their own lawful permanent resident status and evidence of the relationship to the adult child, such as a birth certificate. Once the petition is approved, the adult child will need to complete the green card process through consular processing or adjustment of status, depending on their current immigration status and location.
It's important to note that the green card process for adult children of LPRs can be complex and may involve multiple steps and requirements. It may be helpful to consult with an experienced immigration attorney or other qualified professional to understand the specific requirements and options available.