"Book of Meridians" and "Basic Questions" most likely underwent many significant revisions during their transmission to the Immortal Families, and even Penglai presented several versions of "Book of Meridians." The "Basic Questions" that were in the hands of Yan Jiyue and her sister, although inherited from their troublesome old fox mother, showed that the sisters' cultivation levels were only at the Nascent Soul Realm and had not fully inherited the teachings.
Interestingly, "Huan's Dual Cultivation Techniques" was quite fascinating. This dual cultivation method of qi conditioning and foundation building even included many illustrative sketches. If Li Fan was not mistaken, this could have been intended as introductory education for the imperial disciples of the Immortal Emperor's lineage, and might share the same origin as "The Internal Classic of the Immortal Emperor," laying the foundation for secret techniques.