We have studied mixed mesomorphism in four binary systems comprising two azo-ester mesogens, viz. 4-(4-n-alkoxybenzoyloxy)3-methylphenyl azo-2 and 4-dimethylbenzenes (where n-alkoxy is n-butoxy or n-hexyloxy), and two ester nonmesogenic and mesogenic components, viz. 4-nitrophenyl-4-n-alkoxybenzoates (where n-alkoxy is n-butoxy or n-hexyloxy). All the four binary systems are mesogenic in nature, showing nematic phase with threaded/marble texture. The phase diagrams of the binary systems are plotted and eutectic transition temperatures and maximum mesophase ranges of the nematic mesophase in all the systems are determined.