diff --git a/umap/static/umap/js/modules/sync/engine.js b/umap/static/umap/js/modules/sync/engine.js
index f7aefd66..c5d75000 100644
--- a/umap/static/umap/js/modules/sync/engine.js
+++ b/umap/static/umap/js/modules/sync/engine.js
@@ -54,9 +54,7 @@ export class MessagesDispatcher {
           metadata.featureType
         )
         if (featureTypeExists) {
-          const updater = this.updaters[metadata.featureType]
-          console.log(`found updater ${metadata.featureType}, ${updater}`)
-          return updater
+          return this.updaters[metadata.featureType]
         }
       case 'map':
       case 'datalayer':
@@ -67,7 +65,7 @@ export class MessagesDispatcher {
   }
 
   dispatch({ kind, ...payload }) {
-    console.log(kind, payload)
+    console.log('received message', kind, payload)
     if (kind == 'operation') {
       let updater = this.getUpdater(payload.subject, payload.metadata)
       updater.applyMessage(payload)
diff --git a/umap/static/umap/js/modules/sync/updaters.js b/umap/static/umap/js/modules/sync/updaters.js
index 080cdf72..359e5bdd 100644
--- a/umap/static/umap/js/modules/sync/updaters.js
+++ b/umap/static/umap/js/modules/sync/updaters.js
@@ -48,16 +48,19 @@ class BaseUpdater {
 
 export class MapUpdater extends BaseUpdater {
   update({ key, value }) {
-    console.log(key, value)
     this.updateObjectValue(this.map, key, value)
     this.map.render([key])
   }
 }
 
 export class DataLayerUpdater extends BaseUpdater {
+  upsert({ key, metadata, value }) {
+    // Inserts does not happen (we use multiple updates instead).
+    this.map.createDataLayer(value, false)
+  }
+
   update({ key, metadata, value }) {
     const datalayer = this.getDataLayerFromID(metadata.id)
-    console.log('datalayer', datalayer, key, value)
     this.updateObjectValue(datalayer, key, value)
     datalayer.render([key])
   }
diff --git a/umap/static/umap/js/umap.js b/umap/static/umap/js/umap.js
index db4419ca..162d2763 100644
--- a/umap/static/umap/js/umap.js
+++ b/umap/static/umap/js/umap.js
@@ -812,11 +812,11 @@ U.Map = L.Map.extend({
     return L.Map.prototype.setMaxBounds.call(this, bounds)
   },
 
-  createDataLayer: function (datalayer) {
+  createDataLayer: function (datalayer, sync) {
     datalayer = datalayer || {
       name: `${L._('Layer')} ${this.datalayers_index.length + 1}`,
     }
-    return new U.DataLayer(this, datalayer)
+    return new U.DataLayer(this, datalayer, sync)
   },
 
   newDataLayer: function () {
diff --git a/umap/static/umap/js/umap.layer.js b/umap/static/umap/js/umap.layer.js
index b154bc15..f517fd3c 100644
--- a/umap/static/umap/js/umap.layer.js
+++ b/umap/static/umap/js/umap.layer.js
@@ -521,7 +521,7 @@ U.DataLayer = L.Evented.extend({
     editMode: 'advanced',
   },
 
-  initialize: function (map, data) {
+  initialize: function (map, data, sync) {
     this.map = map
     this._index = Array()
     this._layers = {}
@@ -605,6 +605,12 @@ U.DataLayer = L.Evented.extend({
     // be in the "forced visibility" mode
     if (this.autoLoaded()) this.map.on('zoomend', this.onZoomEnd, this)
     this.on('datachanged', this.map.onDataLayersChanged, this.map)
+
+    if (sync !== false) {
+      const { engine, subject, metadata } = this.getSyncMetadata()
+      const geoJSON = this.umapGeoJSON()
+      engine.upsert(subject, metadata, geoJSON)
+    }
   },
 
   getSyncMetadata: function () {
@@ -612,7 +618,7 @@ U.DataLayer = L.Evented.extend({
       engine: this.map.sync,
       subject: 'datalayer',
       metadata: {
-        id: this.umap_id, // XXX: should we specify it's the layerID here?
+        id: this.umap_id,
       },
     }
   },