earlier order sequence was 1,2,3,4,5, etc, I reformed it to another sequence 1,3,5,7,9, etc which is incrementing in step of 2 (not 1).
By using this sequence we can allot an item order to either 2 (before) or 4(after) with respect to 3 (item selected in the list). and by reorder function again order is converted to 1,3,5,7, etc.