Tasks/Subtasks drap-n-drop in-to stories

Hi, with the new next-gen project, I understand you are working on adding subtasks, but I was hoping you also can add a feature to drag-n-drop the tasks into a story and automatically that converts to a sub-tasks within that story. and if a sub-tasks is part of another story and if we can drag-n-drop that into another story, that will also be great.