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Correlated transition-metal oxides continue to attract widespread interest due to the abundance of exciting phenomena arising from the strong interactions between several degrees of freedom. Among them, the bilayered ruthenate Sr₃Ru₂O₇ is known for its dramatic response to chemical substitution among other external stimuli. The remarkable evolution of the magnetic ground state due to a partial substitution of Ru by Mn in Sr₃(Ru_1-xMn_x)₂O₇ has been characterized through our experimental investigations. Due to the inherent ferromagnetic (FM) and antiferromagnetic (AFM) interactions in x = 0, introducing Mn results in initially an E-type AFM ordering (x < 0.2) then a spin glass (SG) behavior for 0.20 < x < 0.66 before forming a canted AFM ordering in x = 1 (Sr₃Mn₂O₇). The wide range of the SG state indicates strong competition of FM and AFM interactions. A complete phase diagram of Sr₃(Ru_1-xMn_x)₂O₇ will be presented.