sorting surfaces and intersection points

hello,

im struggling with the logic behind this definition... ive reached a point where i have a list of surfaces that are being intersected by a list of lines and id like to cull the redundant surfaces... meaning,

id like to sort out the intersections per line and then the point with the lowest z value among those lists.

im thinking i'll need to sort the points based on an if statement that decides if a point is on a line, but i cant figure it out.

i hope this makes sense. any ideas? files attached.

g