Create two functions, either from file import or just manual poly-line (probably ok, I used imported from two files).
Create a 3rd function, type math expression. Refer to the 1st and 2nd function as input parameters to the math expression x and y.
I just used x+y as the actual expression.
Then right click the Math Expression function you created and select Copy Object.
Now the new copied function does have the correct x-function reference, but the y-function reference is reset to None.
Create two functions, either from file import or just manual poly-line (probably ok, I used imported from two files).
Create a 3rd function, type math expression. Refer to the 1st and 2nd function as input parameters to the math expression x and y. I just used x+y as the actual expression.
Then right click the Math Expression function you created and select Copy Object. Now the new copied function does have the correct x-function reference, but the y-function reference is reset to None.