You explanation of your new scenario is correct - but it is not the same as 2inquisitive's scenario. In 2inquisitive's scenario, there is only one location of interest in Earth's frame - not three. The are three events of interest in Earth's frame - but they all happen at the same place. In your scenario, you have three different locations in Earth's frame, hence it is a different problem. This is the core of the problem in 2inquisitive's scenario - in Earth's frame, the end points of the interval of interest are in the same place. In your alternative scenarios, you are choosing events which are not in the same place in Earth's frame, which is why you get a different result. If you want to change the scenario, make sure that the interval end points are in the same place in Earth's frame. Please, What problem are your answering in 2inquisitive's scenario? Can you state the problem that you are answering without reference to the laser events?