The dense environment of galaxy clusters influences galaxy evolution by affecting their morphology and/or star formation activity. Galaxy clusters have a higher fraction of red passive galaxies near their cores, while the fraction of blue star-forming galaxies increases with cluster centric radius. However, little work has been done studying the galaxy population in clusters as a function of the cluster dynamical state. Such works have not settled the question whether the merging process increases or quenches the star formation activity of their galaxies during the process. As a first step to improve how extreme dynamical state changes the galaxy population, we are building a large sample of merging clusters. There are several dynamical state proxies that can be used to determine the dynamical state of a cluster, one of them is by using the departure from a Gaussian shape of the velocity distribution. In this talk, I will present preliminary results of 15 massive SZ-selected merging galaxy clusters candidates at 0.3 < z < 0.65 observed with GMOS-S in 2018B semester. In addition, I will present a detailed analysis of SPT-CLJ0307-6225, an X—ray confirmed merging cluster candidate at z~0.579, based on data collected with MUSE.