Folie

5 minutes ago, Ontarkie said:

I don't know how it worked years ago, but did your grandfather ever register your father's birth? Did he ever get a US passport? That is something to look into before anything else. 

Hi!

Yes he did, thankfully (or, as I understand, my dad took his dad to the US Embassy here in London)

I don't think my dad has a social security number, but he does has a US passport (he's had multiple) and travels one a year or so to the US on vacation

Hi there!

So, my parents want to move from England, where we all live and are citizens, to the United States, which where none of us have ever lived, BUT my FATHER is an American citizen, by virtue of HIS father being an American (who moved to the UK after the war)

I don't think it'll be that hard for my (18 y/o) little brother to move out there as he's the son of a citizen, but do any of you guys know the easiest/best way for my mother (who has been married to my US-citizen father for over 20 years) to get out there! - she was looking at green cards but she said that a lot of that stuff was for people planning to get married, or who were just married which isn't exactly right for them and she was wondering if there's an easier way to do it since her husband's a citizen and they've been married for so long?

Also, a tip for the best way for my little brother to get out there would be hugely appreciated also! - I'm staying in Europe myself

Someone suggested an IR-1 visa for my mom but further reading seems to suggest that this is for immediate relatives of RESIDENTS