Sort order issue

Hi, I have a mix of books and unsigned newspaper articles in my project, and according to the Chicago style those unsigned sources should be listed among the books and other sources in the bibliography, but sorted by their secondary title (Newspaper name). I just can’t figure out how to do this.  

I have tried to make a template for unsigned articles in my output style, making secondary title appear first in the bibliography. But the sort order is still based on the title. 

I am not sure, but it seems to me that this would be easy if the Anonymous Works setting would let me sort anonymous sources by secondary title, but there is no such option. Can it still be done?