I live in Colombia and going to China with my family on a work visa

I am U.S. citizen, my kids also but they have Colombian passport and my Husband only Colombian passport. We have the invitation letter from my future job in Qingdao, China. I would like to buy 1 one tickets from Bogota, Colombia to Los Angeles and then Los Angeles to Qingdao. To get my Z visa do I need to buy a round trip ticket at least from L.A. to Qindao or can this be a one way. If I eventually get a one way will they let me fly when I get to the airport? Please specify. Thanks.