The easiest way to do this is simply graft the points coming out of each Populate 2D component so that each point is on it’s own branch. Then, use a Merge component to merge the two datatrees together so that the point on the first branch of the first Populate 2D component is merge with the point on the first branch on the second Populate 2D component… and so on. I then use a Polyline component instead of a Line component… but you could isolate each point on the branch (now there are only two points per branch) and use those to create a Line if you wanted. A polyline component seemed simpler.