New experimantal implementation for Highcharts 4.1 is available at http://jsfiddle.net/gh/get/jquery/1.7.2/highslide-software/highcharts.com/tree/master/samples/highcharts/studies/alignthresholds/.
This implementation looks a the threshold on the primary axis (the one first defined), and aligns the threshold of any following axis to that of the primary axis.Anonymous commented
How to fix the y axis for multiple line in highchart. In my case, each line is coming with its own y axis. how to handle this >