  Effects of backward scattering between fractional quantum Hall (FQH) edge
modes are studied. Based on the edge-state picture for hierarchical FQH
liquids, we discuss the possibility of the transitions between different
plateaux of the tunneling conductance $G$. We find a selection rule for the
sequence which begins with a conductance $G=m/(mp\pm 1)$ ($m$: integer, $p$:
even integer) in units of $e^2/h$. The shot-noise spectrum as well as the
scaling behavior of the tunneling current is calculated explicitly.
