Require at least one checked checkbox in a checklist

Hi,

Is there a way to make sure that at least one checkbox keeps selected?
In my case I have two checklist with 2 options. But I need to keep at least one selected at all times.
I haven’t found any obvious way to accomplish this.

I tried solving it with a callback but that would have resulted in an infinite loop, because my input and output
were the same.

Thanks