My sister applied multiple colleges for master with an opportunity for TA, RA, and other assistant ship. She applied for visa and got visa for XYZ university but without TA. She is travelling tomorrow to USA to attend late August orientation with ZYZ university. Luckily, She got a letter today from ABC university stating that she got TA in their university.I want to send her to ABC university whose orientation also begin late August.

What does she need to do to goto ABC university? Can she just ignore XYZ university and show up at ABC university?

Any advice from expert and experienced will be highly appreciated.

Thanks!!