X-Form: surface poles associated to points

In a previous thread,  taught the technique of associating surface poles to pre-fined points.

 

Here I observed an odd thing about X-Form.

 

As shown below, I created a 2×2 face, X-Form/dragged its poles to be coincident with the ends of four lines. When I changed the lengh of the lines, the face did change with them. But under the feature X-Form, there is no patents of lines listed! And the lines have no children!

 

Is there anything wrong? Thanks!