We investigate the structure of non-stabilizerness in interacting disordered fermionic systems, quantified via the fermionic stabilizer R'enyi entropy (SRE). To resolve how non-stabilizerness is distributed across scales, we introduce a (multipartite mutual SRE), an inclusion–exclusion combination of subsystem SREs that reduces to the mutual SRE for two parties. Unlike the optimization-based notion of non-local non-stabilizerness, it is not a monotone and can be negative; it vanishes on any state that factorizes across a nontrivial partition, and its sign distinguishes synergistic from redundant sharing of non-stabilizerness among the parties. We illustrate the measure on paradigmatic multipartite states and apply these diagnostics to the Sachdev–Ye–Kitaev model and its mass-deformed and sparse variants. At finite temperature, typical pure-state representatives of the Gibbs ensemble, namely thermal pure quantum (TPQ) states and energy eigenstates, carry far more non-stabilizerness than the Gibbs density matrix itself, the gap being largest at high temperature, where the thermal entropy is largest. Non-stabilizerness is thus not inherited by the coarse-grained thermal description, which in a holographic reading means that it is concealed in the black-hole microstates. In $𝒩=2$ supersymmetric SYK, fortuitous BPS states carry non-stabilizerness intermediate between $Q$-exact and Haar-typical states in the central $R$-charge sectors, while the multipartite measure reveals a sector-dependent pattern that differs from that of the total SRE.