pastjob

I have friends that have come here from russia, they were allowed visas but their 2 children did not receive visas. they are hee without their children. the wife went back to try and bring her children here to the us but were denined visas, she will come back here without here children again. does anybody have any idea on what needs to be done to bring the kids here??? I am trying to help these people but I don't know what to tell them. I am A US citizen, is there anything I can do? Please help