A giant spin splitting has been observed in surface alloys on noble metal (111) surfaces as a result of a strong structural modification at the surface as well as the large atomic spin-orbit interaction (SOI) of the alloy atoms. These surface alloys are an ideal playground to manipulate both the size of the spin splitting as well as the position of the Fermi level, as it is possible to change the atomic SOI as well as the relaxation by varying alloy atoms and substrates. Using (spin-and) angular-resolved photoemission spectroscopy in combination with quantitative low-energy electron diffraction, we have studied the mixed binary BixSb1-x/Ag(111) surface alloy where we observed a continuous evolution of the band structure with x and the mixed ternary Bi0.3Pb0.35Sb0.35/Ag(111) surface alloy.