Orb-relaxed Sm8 Fe92 B4 C4 boride candidate. CIF SHA256 b3b5df2817b89d741fa0970edebfd1880888f4b218d4eecfca5e60c3145ddb6d. Unconstrained variable-cell ML relaxation; no DFT. Ouro same-formula novelty, hull stability and magnetic performance remain under review; cross-composition framework novelty is separate. GPAC-authored complete B4-to-C substitution on a previously generated Nd/Sm directional boron-pair-vacancy support. All92Fe sites are retained; this is a new B/C filling, not a new occupied framework. The computational Y2Fe23B3 archive is the attributed ancestor; the vacancy support and this alloy are not published experimental structures. This is a chemical-order hypothesis, not a claim of an additional framework family. Chemical fillings of the existing directional B-pair-vacancy support derived from the computational Y2Fe23B3 archive. Replace exactly one of two complete four-site B orbits with C. Retain eight Nd or Sm, all92Fe sites, the other four B, every position and the exact original metric. These are four fillings on one occupied support, not four new frameworks. Known cubic parent metal ancestry remains explicit. No source property or experimental phase identity is transferred. Source: https://doi.org/10.1103/PhysRevB.70.144107