Clarification regarding Immigration at US Port of Entry

[Ashnvai]

Hi,


My young/ unmarried IT employed sister had her visa rejected a month ago and when we reapplied, she got it stamped. At the consulate she mentioned she is travelling for 3 weeks, whereas now I want to bring her for 6 months. Her tickets are also booked that way.

She has sebatical leave approved for 6 months from her company (since Dr has asked her to stay away from electro magnetic rays for 6 months). Can she tell the Immigration officer @ chicago that she wants to be in the US on a holiday for 6 months, since she has been asked to stay away from EM rays by Dr.
What are the documents she should carry with her?

Kindly help me with an answer asap.

[immihelp]

That is not the valid reason to be in the U.S. She can stay at home in her home country or tour around her own country.

Justify longer stay with valid reasons such as a lot of tourism.