Here is a start on a formalization. Narratives are first class objects. We will be interested in a relation elaborates(N2,N1) asserting that narrative N2 is an elaboration of narrative N1. Intutively, narratives are collections of events and situtaions and relations among them. Tentatively, we will not use sets in our formalism. Instead we make the narrative an additional parameter of sentences concerning situations and events--thus we have occurs(e,s,N). Entering a context associated with the narrative N permits writing occurs(e,s) as has been our custom.
There are two ways of looking at narratives that elaborate other narratives, and maybe we need both of them.
Suppose we have elaborates(N2,N1). We may be asserting that N1 occurred, and N2 also occurred and gives more detail. On the other hand, we may regard N2 as a mere hypothetical elaboration of N1, even a counterfactual elaboration.
We need parts of narratives, and an axiom saying that an elaboration of a part of a narrative extends to an elaboration of the whole in the obvious way.