diff --git a/calendar/experiments/calendar/ext-calendar-utils.sys.mjs b/calendar/experiments/calendar/ext-calendar-utils.sys.mjs
index 4b0bb34..ed5fbdd 100644
--- a/calendar/experiments/calendar/ext-calendar-utils.sys.mjs
+++ b/calendar/experiments/calendar/ext-calendar-utils.sys.mjs
@@ -63,6 +63,8 @@ export function convertCalendar(extension, calendar) {
     name: calendar.name,
     url: calendar.uri.spec,
     readOnly: calendar.readOnly,
+    visible: !!calendar.getProperty("calendar-main-in-composite"),
+    showReminders: !calendar.getProperty("suppressAlarms"),
     enabled: !calendar.getProperty("disabled"),
     color: calendar.getProperty("color") || "#A8C2E1",
   };
diff --git a/calendar/experiments/calendar/parent/ext-calendar-calendars.js b/calendar/experiments/calendar/parent/ext-calendar-calendars.js
index c361a40..440c028 100644
--- a/calendar/experiments/calendar/parent/ext-calendar-calendars.js
+++ b/calendar/experiments/calendar/parent/ext-calendar-calendars.js
@@ -19,7 +19,7 @@ this.calendar_calendars = class extends ExtensionAPI {
     return {
       calendar: {
         calendars: {
-          async query({ type, url, name, color, readOnly, enabled }) {
+          async query({ type, url, name, color, readOnly, enabled, visible }) {
             let calendars = cal.manager.getCalendars();
 
             let pattern = null;
@@ -56,6 +56,10 @@ this.calendar_calendars = class extends ExtensionAPI {
                   matches = false;
                 }
 
+                if (visible != null & calendar.getProperty("calendar-main-in-composite") != visible) {
+                  matches = false;
+                }
+
                 if (readOnly != null && calendar.readOnly != readOnly) {
                   matches = false;
                 }
@@ -87,6 +91,12 @@ this.calendar_calendars = class extends ExtensionAPI {
             if (typeof createProperties.color != "undefined") {
               calendar.setProperty("color", createProperties.color);
             }
+            if (typeof createProperties.visible != "undefined") {
+              calendar.setProperty("calendar-main-in-composite", createProperties.visible);
+            }
+            if (typeof createProperties.showReminders != "undefined") {
+              calendar.setProperty("suppressAlarms", !createProperties.showReminders);
+            }
 
             cal.manager.registerCalendar(calendar);
 
@@ -114,6 +124,14 @@ this.calendar_calendars = class extends ExtensionAPI {
               calendar.setProperty("disabled", !updateProperties.enabled);
             }
 
+            if (updateProperties.visible != null) {
+              calendar.setProperty("calendar-main-in-composite", updateProperties.visible);
+            }
+
+            if (updateProperties.showReminders != null) {
+              calendar.setProperty("suppressAlarms", !updateProperties.showReminders);
+            }
+
             for (let prop of ["readOnly", "name", "color"]) {
               if (updateProperties[prop] != null) {
                 calendar.setProperty(prop, updateProperties[prop]);
@@ -237,6 +255,12 @@ this.calendar_calendars = class extends ExtensionAPI {
                     case "uri":
                       fire.sync(converted, { url: value?.spec });
                       break;
+                    case "suppressAlarms":
+                      fire.sync(converted, { showReminders: !value });
+                      break;
+                    case "calendar-main-in-composite":
+                      fire.sync(converted, { visible: value });
+                      break;
                     case "disabled":
                       fire.sync(converted, { enabled: !value });
                       break;
diff --git a/calendar/experiments/calendar/schema/calendar-calendars.json b/calendar/experiments/calendar/schema/calendar-calendars.json
index 2c410b1..388fae5 100644
--- a/calendar/experiments/calendar/schema/calendar-calendars.json
+++ b/calendar/experiments/calendar/schema/calendar-calendars.json
@@ -13,6 +13,8 @@
           "url": { "type": "string" },
           "readOnly": { "type": "boolean" },
           "enabled": { "type": "boolean" },
+          "visible": { "type": "boolean" },
+          "showReminders": { "type": "boolean" },
           "color": { "type": "string", "optional": true },
           "capabilities": { "$ref": "CalendarCapabilities", "optional": true }
         }
@@ -25,6 +27,8 @@
           "url": { "type": "string" },
           "readOnly": { "type": "boolean" },
           "enabled": { "type": "boolean" },
+          "visible": { "type": "boolean" },
+          "showReminders": { "type": "boolean" },
           "color": { "type": "string", "optional": true }
         }
       },
@@ -104,6 +108,7 @@
               "name": { "type": "string", "optional": true },
               "color": { "type": "string", "optional": true },
               "readOnly": { "type": "boolean", "optional": true },
+              "visible": { "type": "boolean", "optional": true },
               "enabled": { "type": "boolean", "optional": true }
             }
           }
@@ -131,6 +136,8 @@
               "url": { "type": "string" },
               "readOnly": { "type": "boolean", "optional": true },
               "enabled": { "type": "boolean", "optional": true },
+              "visible": { "type": "boolean", "optional": true },
+              "showReminders": { "type": "boolean", "optional": true },
               "color": { "type": "string", "optional": true },
               "capabilities": { "$ref": "CalendarCapabilities", "optional": true }
             }