I am new for houdini. I got a model, then I used add sop to delete geo but keep the point, then i want to connect points to a curve. I don't know how can i choose point from add sop. There are around 600 points in the sense, so I use group sop for the point, but I found out I cannot choose the group in the curve coordinates. Do your guys a have some idea?

You will need both an add node and a polyspline node. If you download the file in my question above about closing the ends of a sweep nurb equivalent, you can see how I connected points with add and polyspline nodes.