I deleted your replied in the forwarded thread.
Indeed a line or a graph must sit in one coordinate space.
In the example I sent you the axis is broken (like in your example) therefore that’s two coordinate space. So it really depends what you want to do and how … but imagine your two lines are in two coordinate spaces in Y with X in the same coordinate space like in my example then a point on the border in the first pad will coincide with a point on the border in the 2nd pad if they have the same X