Who can be valid sponsor for first time visit to Shanghai?

My sister works in shanghai and she invited me, my parents and my girlfriend to visit her there. It is my girlfriends's first time to shanghai. The problem is she is unemployed and doesn't have at least 100k daily balance in her account. My sister paid for our tickets and we will be staying in her apartment. Can my sister be considered her sponsor since she will basically pay for the whole trip which includes: tickets, accomodations and expenses?