Multiple inputs on a filter

I am trying to build a polyline step by step by forming it using a pair of points then merging so they preserve the order that I want, but I got some problems catching the other inputs, I can only use the first one. How can I do this? How do I get the other inputs?

Every Extract Selection posses a pair of points to form a simple polyline.
By forming then and merging, I expect to form the outline.