I have read a book containing the first three novels of Asimov's Foundation series, as well as a book containing all of The Hitchhiker's Guide to the Galaxy novels.

However, when I joined a challenge that only included the first novel of each series, the novel wasn't marked as "complete".

Could the system be modified to recognize that those novels were actually read?

The Storygraph already knows if a book contains more than one novel in a series. Perhaps that information could be used in challenges to determine which novels were read?