Is there a way to parent an objects position to another objects position in Nuke, so they move parallel to each other?
You can simply edit the expression values:


create a new Transform Node by hitting T
drag and drop the translation values by holding CTRL from original transform node to the new one (this should create a green line between that nodes)
right click the translation curve icon of the new transform node to open up the Edit Expressions Window 
in this window you can do some math with the existing y or x values to move the the child node