You can't turn off all highcharts. How to make such a thing?

Question

Highcharts

Hello. There are 2 regular schedules. How to implement so that it would be impossible to turn them all off? That is, if we turn off the first, then the second cannot be turned off until we turn on the first. That is, so that there would be no empty space when they turn off 2 at once. I looked through a bunch of documentation and examples, did not find a solution. I would be grateful if anyone can share an example.