Localization multi turtlebots with one workstation

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I'm kinda new to ros and turtlebot. I'm trying to work on formation control of multi robots and I'm using turtlebots for this purpose. Is there anyway to use only one workstation and 3 turtlebots as three masters? I tried to define 3 different ROS_MASTER_URI on the workstation; however it only recognizes the last one. Also for the robot's localizations I know there is AMCL for that purpose, but I wanna define a local coordinate for all turtlebots and measure their x and y with relative to that coordinate. Does anyone have any idea? Much appreciated in advance.