Chicago Manual of Style 14.114
I use the equivalent of whole primary sources contained within an anthology on a regular basis. As it is, there is no way to chose a specific "Type" that produces a properly formatted bibliographic entry. I imagine it would be rather simple to modify one of the existing types, such as "Book Section" to produce the required results. The alternative is manually altering all of my bibliographies which seems to decrease the utility of Zotero. Thanks.
And adding item types is neither quick nor simple - it involves changes in Zotero code, changes in Zotero sync code, changes in the citation style language that is used in multiple ref managers as well as changes in citation styles.
I do want to point out again, though, that CMoS does not require the type of citation you want. It is a "may" rule not a "should" or "must" rule.
My understanding is that both are correct here.
There are two alternatives that might be more promising:
1. Finding a way to fold this into a more generic type - one that might be able to cover plays (and maybe poems?) as well, for example.
2. Finding a way to add a field to the book section item type - again, a field that's as generic as possible - that would allow a style to distinguish between the two.