Eligible family inclusion and any child-age protection require individualized review. The Child Status Protection Act can affect the calculation, but a child's age is not automatically frozen merely by investing or filing the petition, and visa availability also matters.
Bring the actual dates before setting a school or moving timetable
Record birth dates, the petition's filing history, and the family's intended arrangements, and ask counsel to apply the applicable rules individually rather than relying on a general estimate drawn from another family's case. A school enrollment decision should not be made as though it guarantees a particular immigration outcome. Derivative eligibility concerns a spouse or unmarried child under 21, subject to any applicable CSPA calculation.
Government filing fees for the immigrant petition, the residence application for each family member, and the later petition to remove conditions, all listed in the USCIS fee schedule; plus regional-center administrative fees, legal, accounting and translation costs. Write down what the household needs to know that a promoter will not volunteer: which family members are covered, what happens to the derivatives if the principal's petition is denied, and what documents each person will eventually have to produce.