Is this possible to do automatically? I need to illustrate that the task isn't 16 weeks long (like the first image), it's 12 weeks with a 4wk break driven by the non-working time (red shading) which I've mocked up in the second image.

The task may also move, but the non-working time won't (which is specific to this task).

I know I can manually split the task (which I've shown in the 3rd image) however when the programme changes that split will move from the non-working time and I need to manually drag it around.

While it is possible to change the color of non-working time, it seems that not all tasks can be automated.