Thank you for a feedback! At the beginnig I tried to make simple levels for a little practice because it would be difficult to explain this system to players. There is a 3D control point that copies the Y coordinate (vertical axes) of the active character and the X or Z coordinate (horizontal axes) (depending on the active player) of the active character (other horizontal axes of the inactive player will not be copied). And everything else works simpler, the checkpoint of one character and the checkpoint of another character will be a projection of the 3d checkpoint on their axis.
Like I said, it's hard to explain and I'm open to any ideas :)