Character formulas for Kirillov-Reshetikhin modules via folding of supercharacters of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.svg"> <mml:mrow> <mml:mi mathvariant="fraktur">gl</mml:mi> <mml:mo>(</mml:mo> <mml:mi>M</mml:mi

We derive decomposition formulas for supercharacters of quantum affine ortho-symplectic superalgebras and twisted quantum affine superalgebras into supercharacters of their finite-type quantum sub-superalgebras, by employing Cauchy-type identities for supersymmetric Schur functions. These formulas are obtained via a folding (reduction) procedure applied to the supercharacters of the finite-dimensional general linear Lie superalgebra $\mathfrak{gl}(M|N)$. As a special case, our results provide explicit character formulas for a class of Kirillov--Reshetikhin modules of quantum affine algebras (and their Yangian counterparts), thereby proving a previously proposed conjecture derived from Bethe ansatz analysis (arXiv:2309.16660).