Our children used Chinese Travel document when they were young, can we not use it anymore?

Our children used Chinese travel documents when they were young because at the time we are not US citizen yet. But now we are U.S. citizen and we apply Chinese Visa to travel back to China. We also want our children to apply for Chinese Visa to travel back. But the consulate said that we must use Travel Document again for the kids. We don't want travel document for our kids. We don't want our kids to be considered as Chinese Citizen anymore. How can we tell Embassy about that?