Sponsor domicile query

[jimmy_]

I am a US citizen (having been born in the USA) and am sponsoring my parents to go back to the United States (they are UK citizens) under a family reunification visa.

I have been living in the UK and understand that I have to go back to the USA to prove my intention to domicile there, ie. get a job, get a tenancy on a house etc. But I just wondered after my parents have been given the visas, do I have to stay in the USA for their visas to remain valid or can I move back to the UK and leave them there without me?

[immihelp]

If you are going to move back to the UK and your parents in the US, what kind of family reunification is that?

[jimmy_]

we have other family in the US and my sister is joining them next year, but I am the only person who can sponsor them. I may or may not return to the UK depending on my work, but I would just be grateful to know the terms of the visa so I can make an informed decision!