Legal permanent residents may file a family-based immigrant visa petition for their unmarried sons and daughters who are not young enough to be considered children. They may all be petitioned for at the same time. The sons and daughters would all be classified under the F-2B category. To determine how long it would take before an immigrant visa becomes available for the permanent resident's sons and daughters to come to the United States, refer to the current visa bulletin. A link has been provided below.