You can drag and drop to rearrange the order. It even works well on touch-screens.

Serialised Output (per list)

Draggable Handles 1
  1. Item 1
  2. Item 2
    1. Item 3
    2. Item 4
    3. Item 5
      1. Item 6
      2. Item 7
      3. Item 8
    4. Item 9
    5. Item 10
  3. Item 11
  4. Item 12
Draggable Handles 2
  1. Item 13
  2. Item 14
  3. Item 15
    1. Item 16
    2. Item 17
    3. Item 18
Draggable Handles 3
  1. Item 13
  2. Item 14
  3. Item 15
    1. Item 16
    2. Item 17
    3. Item 18