While you’re dragging an independent point, you can merge it to another point or to a path (the merge target), provided that the merge target is not itself a descendant of the point being merged. Hold the point you want to merge over the merge target until animated arrows appear, and then release to complete the merge. If you decide not to merge it, just drag the point away from the merge target.

If you merge a point by mistake, or merge it to an unintended target, choose Edit | Undo.