Hi, I'm a UK citizen wishing to live/work in the USA. My Father was planning to sponsor me, but unfortunately he died recently; my 23 year old half sister who is registered mentally disabled is the only other person who is able to sponsor me, she is an american citizen. Is this possible, or do sponsors need to be completely independent? The main purpose of my green card request is to be closer to my Sister as her Mother is ill, so it's important she has family support since we've just lost our Father; Her Mother is willing to sign any paperwork on my half sisters behalf. I am financially independent, currently working as a self employed currency trader part-time, but also trained and working as a Business Analyst for an investment bank on a contract basis.