High-precision $D^0 to V^+P^-$ - more accurate than $D^0to P^+P^-$

Recently we derived a nonlinear U-spin amplitude relation for $D^0to P^+P^-$, $P=pi, K$, predicted to hold up to fourth order U-spin breaking terms of order $10^{-3}$. Here we study a similar relation for $D^0to V^+P^-, V =rho, K^*(892), P = pi, K$, expected to hold at an even higher accuracy of order $10^{-4}$. We confirm this prediction in spite of a large experimental error of about 20% in the amplitude of $D^0to K^{*+}pi^-$. We also comment briefly on U-spin breaking in $D^0to P^+V^-$.