(I think that commands needs to be renamed.. My head almost exploded when I read it
)
So instead of syncing source panel with target panel. you want to sync the target panel with source panel.
I see if it is possible to add a command for that.
In the meanwhile you can do that. using Alt + Left/Right Arrow.
if focus (source panel) are on the left side you press Alt+Left (Send target path to the left)
If focus (source panel) are on the right side you press Alt+Right (Send target path to the right)
You can also do the reverse.. if focus are in the left side and you press Alt+Right you will send the path of the item in focus to the right.