Pushpa,

Just wanted to let U know that they need to take a medical insurace(tht covers accidents too) for them all before they go there...Medical expenses are very high & it's advisable to take an insurance as we never know when it'll be required... they can take a insurance that covers them for a month(the ones that the tourists take) or so & then they can find some good insurance plans that'll suit them later...

Considering the details U've given, the wise & economical option would be for ur sis & kids to stay back in India for a few months till ur BIL settles in a job there... Also, if ur is is not comfortable driving a car, please ask her to learn it before she goes there...

Please check these sites... they have many useful info...
http://www.newcomersguideusa.com
http://www.lifeintheusa.com/