How do I change ukes position without changing Tori's position?

You can use the teleport script by Dansan123 for that. Don't know if there's another way to do it.
http://forum.toribash.com/script.php?tag=teleport

Thank you for your answer

You use the engage player position in the game rules

enter in - 0.00,0.00,0.00,0.00,0.00,0.00 - the first three are tori's position and the last three are ukes, or its the other way around. Out of the three there is up/down, left/right and forwards/ backwards. It goes in the negatives for the other direction.

Play around with the axis and you will figure it out quickly.
You can also use it in multiplayer in any mod, so if its parkour you can place the tori's in a different area.