Is there anything I can do to help my younger brothers obtain visas so that they may come to visit

Visiting visas are given in the discretion of American consulates and embassies. Most adjudications are based upon whether consular officers believe that the applicants will return to the home country after a period of visit to the States. You can of course write letters of invitation and promised to support them during the time that they are here, but it would probably be better for your brothers to establish some roots such as working or going to school for a period of time before reapplying for visitors visas. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.