Pellet samples of $Rb_{1-x}(NH_4)_xH_2PO_4$ and $Rb_{1-x}(NH_4)_xH_2P_{1-y}As_yO_4$ mixed solid solutions are studied by dielectric measurements to obtain complete phase diagrams for RADP-x and RADPA-xy, thus complementing previous partial phase diagram of RADPA-xy mixed crystal system. Phase boundaries of both ferroelectric and antiferroelectric sides between long range ordered phase and proton glass phase are given a close examination to confirm phase coexistence.