  We investigate a special class of Poisson--Lie T-plurality transformations of
Bianchi cosmologies invariant with respect to non-semisimple Bianchi groups.
For six-dimensional semi-Abelian Manin triples $\mathfrak{b}\bowtie
\mathfrak{a}$ containing Bianchi algebras $\mathfrak{b}$ we identify general
forms of Poisson--Lie identities and dualities. We show that these can be
decomposed into simple factors, namely automorphisms of Manin triples,
B-shifts, $\beta$-shifts, and "full" or "factorized" dualities. Further, we
study effects of these transformations and utilize the decompositions to obtain
new backgrounds which, supported by corresponding dilatons, satisfy Generalized
Supergravity Equations.
