I'm wonder, if this circuit make sense ...
I'd like to combine 4 Vref, but worried about current flow, so adding buffer to each in assumption opamp will do it better ,
then probably not bad to try filtering a noise; so R10 + C6,C1 (electrolytic) appears, to decrease a current leakage. And R2, R4 - in opamp loop for Vdrop compensation ...
4 such units in parallel, ( not 2 )
then amplification module to +10V ..