Sponsoring sister's GC while her children are on F1

[vki01]

I am a US citizen. I am trying to sponsor my sister's GC. Both of her children are currently studying in US on F1 visa. How will the GC application affect:

1. The children's F1 visa or H1 visa?
2. My sister's travel to US on a visitor visa (valid until 2016) after application for her GC?

Thanks

[immihelp]

1. Doesn't matter.
2. Doesn't matter.