  We develop a general spectral framework to analyze quantum fractional revival
in quantum spin networks. In particular, we introduce generalizations of the
notions of cospectral and strongly cospectral vertices to arbitrary subsets of
vertices, and give various examples. This work resolves two open questions of
Chan et.~al. ["Quantum Fractional Revival on graphs". Discrete Applied Math,
269:86-98, 2019.]
