Let's say I have a scenario like this, viewed from orthographic X perspective (num3):
Both objects are the same length, but the top line is a single, angled edge while the bottom line is flat and divided into six sections. I want to subdivide the top line by inserting a point at the same Y coordinate as the highlighted vertex of the bottom line, without disrupting the angle of the top line.
Subdividing the top edge will insert a new vertex, but only at the midpoint of the edge. With vertex snapping, I can drag the new vertex to the appropriate Y axis coordinate, but this disrupts the angle of the line because it does not affect the vertex's Z axis coordinates.
Edge slide is pretty much what I want, but I can't edge slide a single vertex. How can I make this work?