linkedTo property
The id of another series to link to. Additionally, the value can be ":previous" to link to the previous series. When two series are linked, only the first one appears in the legend. Toggling the visibility of this also toggles the linked series, which is necessary for operations such as zoom or updates on the flowmap series.
API Docs: https://api.highcharts.com/highcharts/series.flowmap.linkedTo
Implementation
String? linkedTo;