What are you going to be working on? If it's just piecing, would get a small 'take to class' machine. I would probably get it from AllBrands and just have it shipped to my sister's house. Save all the packaging and when you are ready to return, repack & ship it back. It's worth the price of shipping not to have to deal with it on the flight.
Another option would be look for a used machine when you get there, and leave it for your sister.
I personally would not try to carry a machine on, especially an expensive one.