[Solved]-Highcharts - How to combine unique legend for multi-series pie chart which perform same action for both series? (like onclick: show/hide)-Highcharts

Normally you should use linkedTo property, but it works only for series not for points. To add linking functionality for points, use the below plugin which links points from different series by name.

(function(H) {
    H.addEvent(H.Point, 'legendItemClick', function() {
        const legendPoint = this;

        this.series.chart.series.forEach(s => {
            if (s !== legendPoint.series) {
                const matchedPoint = s.points.find(p => p.name === legendPoint.name);

                if (matchedPoint) {
                    matchedPoint.setVisible();
                }
            }
        });
    });
})(Highcharts)

Live demo: https://jsfiddle.net/BlackLabel/styhx6do/

API Refernece: https://api.highcharts.com/highcharts/series.column.linkedTo

Docs: https://www.highcharts.com/docs/extending-highcharts/extending-highcharts