  The feasibility of determining $\Delta \Gamma_s / Gamma_s$ from $B_s \to
D_s^{(*)+} D_s^{(*)-}$ decay branching fraction measurements at $e^+ e^-$
colliders running on the $\Upsilon$(5S) resonance is discussed. The expected
accuracies of the $B_s \to D_s^{(*)+} D_s^{(*)-}$ branching fraction
measurements and the $\Delta \Gamma_s / \Gamma_s$ determination with
50fb$^{-1}$ of data at the $\Upsilon$(5S) are estimated using Monte Carlo
simulation. Comparison of that measurement with a directly measured $\Delta
\Gamma_s / \Gamma_s$ value within and beyond Standard Model is discussed. A new
method of estimating $\Delta \Gamma_s / \Gamma_s$ is proposed, based on
comparing the CP-even and CP-odd components in $B^0 \to J/\Psi K^{*0}$ and $B_s
\to J/\Psi \phi$ decays. A comparison of $B_s$ and $B^0$ lifetime measurements
with theoretical predictions is discussed.
