  The decays $B\to\bar{D}^{(*)} \omega\pi$ are very important for the
investigation of $\rho$ excitations and the test of factorization hypothesis
for $B$ meson decays. The $B^{+}\to \bar{D}^{(*)0}\omega\pi^+$ and $B^{0}\to
D^{(*)-}\omega\pi^+$ have been measured by different collaborations but without
any predictions for their observables on theoretical side. In this work, we
study the contributions of $\rho(770,1450)\to \omega\pi$ for the cascade decays
$B^{+}\to \bar{D}^{(*)0} \rho^+ \to \bar{D}^{(*)0}\omega\pi^+$, $B^{0}\to
D^{(*)-} \rho^+ \to D^{(*)-}\omega\pi^+$ and $B_s^{0}\to D_s^{(*)-} \rho^+ \to
D^{(*)-}\omega\pi^+$. We introduce $\rho(770,1450)\to \omega\pi$ subprocesses
into the distribution amplitudes for $\omega\pi$ system via the vector form
factor $F_{\omega\pi}(s)$ and then predict the branching fractions for the
first time for concerned quasi-two-body decays with $\rho(770,1450)\to
\omega\pi$, as well as the corresponding longitudinal polarization fractions
$\Gamma_L/\Gamma$ for the cases with the vector $\bar{D}^{*0}$ or
$D_{(s)}^{*-}$ in their final states. The branching fractions of these
quasi-two-body decays are predicted at the order of $10^{-3}$, which can be
detected at the LHCb and Belle-II experiments. The predictions for the decays
${B}^0 \to{D}^{*-} \rho(770)^+\to {D}^{*-} \omega\pi^+$ and ${B}^0 \to {D}^{*-}
\rho(1450)^+\to {D}^{*-} \omega\pi^+$ agree well with the measurements from
Belle Collaboration. In order to avoid the pollution from annihilation Feynman
diagrams, we recommend to take the $B_s^0 \to D_s^{*-}\rho(770,1450)^+$ decays,
which have only emission diagrams at quark level, to test the factorization
hypothesis for $B$ decays.
