Let the subtasks for a goal be placed under different days but still be linked together

Sometimes you can't finish a whole goal in one shot, so putting it into one day doesn't make sense. But you do still want to actually put it into the calendar. I think the best way would be to allow substasks to be dragged into the calendar, and the system would recognize when all the substasks of a goal have been completed. Anyway, I just want to say I love weekplan! Thanks a lot!