你結婚時女兒>=18歲, 繼父不能為她提出I-130

見: https://www.uscis.gov/tools/glossary/child

a stepchild, provided that the child was under 18 years old when their parent married their step-parent;

法律和中介沒有關係，中介說的不是法律．　看來是移民局以前搞錯了．