There's a lot going on in your demo, but unfortunately I do not see a series in which you add the blue line you show in the first picture.
I resized the window and it still does not appear. Could you specify the place in the code where you add this line?
Here's the
demo: showing how to create a small
yAxis on the bottom of the main
yAxis and add technical indicators in an easy way:
https://jsfiddle.net/BlackLabel/jnL72dz9/
That might help you achieve a similar effect.
Regards,
Jakub