Don't know the answer. You should consult a lawyer.
In my own opinion, you should not try to fly your grandma here. I had a friend who recently moved her 79 old mother here. The mother got paralyzed on the plane. When she got off the plane she was rushed to the hostital and never come out since then. She spent her last 2 years in the hospital until she died. That's why I didn't invite my grandparents here. I want them to see another country but their lives are more important.