Syncing Multiple Motor Drivers
This depends a lot on the interfaces provided by Roboclaw. Best bet is probably step/dir driven from some controller that can calculate synchronous movements. If this is not supported I would look at implementing a ROS bridge for UART communication.

Due to cost of ready made solution I'm trying to implement such synchronized control with CAN and CANOpen - basically position interpolation + buffering + SYNC message to start all axes at the same time. More details available in this paper

https://www.servo2go.com/support/downloads/CoordinatedMulti-AxisMotionControlviaCANbus.pdf

Project is https://distrap.org/ (early development)