The Composite NPF Index (CNI) extends the Neural Pathway Fallacy to belief networks, quantifying systemic epistemic risk. This paper presents the CNI formula (weighted sum with normalised weights), normalisation methods (linear, sigmoid with cultural parametrisation), sampling adequacy, and a gradient‑descent weight update (hypothesis). It introduces the neurodiversity provision (autistic resistance to high‑SE NPFs) and positions CNI within the Fractal Entailment Network (FEN