If you delete 2 + 3, then you just have a segment 1 and segment 4, and this will create a problem, as it should be in sequence 1 and 2.
If all segments exist already then you would need to renumber any remaining segment.
If you delete 2 + 3, then you just have a segment 1 and segment 4, and this will create a problem, as it should be in sequence 1 and 2.
If all segments exist already then you would need to renumber any remaining segment.