Hi Jean Michel,
How about a custom event, you can emit them from the map object and they can be listened on in custom controls. I did a console log as an example, but you can add logic to show/hide the entire control, or add/remove radio buttons as per your requirements: Here is an example:
https://codepen.io/corrigancd/pen/GRedVxX
In your case I think you want to show your custom control, or not, or change its content depending on what radio button is selected in the first control. You can listen to base layer changes (assuming your first control is a leaflet layer control -
https://leafletjs.com/examples/layers-control/) with the below, then fire the custom-event in the codepen to trigger the event in your second control (no need to edit the layer control code itself, the baselayerchange event is built in).
map.on('baselayerchange', (newBaseLayer) => {
// todo - fire a custom event from here, that is listened to in your custom control
console.log('newBaseLayer:', newBaseLayer)
})
Best Regards,
Edwin
Edwin Corrigan