I want sync all my stepper motors using Accelstepper library using arduino uno

Actually I am trying to sync 10 nema 17 stepper motors using i2c communication on 2 arduino, in that I’m using Accelstepper library for acceleration and deceleration actions.
The i2c communication between 2 devices happens correctly… Data sent from master to slave accurately, but the problem is that all the motors are not running in synchronous mode, all motors are behaving asynchronous action.

I want to move all motors with same start and stop time in loop. So please give me any suggestion about this.

Syncing 10 stepper motor is a tedious process. What about the power supply? Do all the motor have same power supply?

How exactly are using i2c to drive stepper motor? Can you share the circuit schematics or any block diagram so as to understand your build setup.?