Measuring $\overrightarrow{B}\rho \pi$ decays and the unitarity angle $\alpha$

The decay mode $\overrightarrow{B}\rho \pi$ is currently studied as a channel allowing us, in principle, to measure without ambiguities the angle $\alpha$ of the unitarity triangle. It is also investigated by the CLEO Collaboration where a branching ratio larger than expected for the decay mode $B^{\pm }\to {\rho }^0{\pi }^{\pm }$ has been found. We investigate the role that the $B^{*}$ and $B_0{(0\mathrm{}}^{+})$ resonances might play in these analyses.