diff --git a/src/router.ts b/src/router.ts
index 33f5f93..5452e9b 100755
--- a/src/router.ts
+++ b/src/router.ts
@@ -159,6 +159,62 @@ export async function init(): Promise<void> {
     if (services.isPaired()) {
       await navigate('account');
     } else {
+      // Check for device addition URL parameter
+      const urlParams = new URLSearchParams(window.location.search);
+      const addToId = urlParams.get('add_to_id');
+
+      if (addToId) {
+        try {
+          // This is a new device trying to join an existing pairing process
+          const pairingProcess = await services.getProcess(addToId);
+          console.debug(pairingProcess);
+          if (!pairingProcess) throw new Error('Non existent process'); // We were given a non existent process
+          const lastCommitedState = services.getLastCommitedState(pairingProcess!);
+          if (!lastCommitedState) throw new Error('Uncommited process'); // We were given an uncommited process
+          console.debug(lastCommitedState);
+          const currentPairedAddresses = lastCommitedState?.public_data['pairedAddresses'];
+          if (!currentPairedAddresses) throw new Error('Not a pairing process'); // We were given probably not a pairing process
+          const decodedAddresses = services.decodeValue(currentPairedAddresses!);
+          console.debug(decodedAddresses);
+          const modalService = await ModalService.getInstance();
+          const result = await modalService.showConfirmationModal({
+            title: 'Ajout d\'appareil',
+            content: `
+              <div class="modal-confirmation">
+                <h3>Ajouter cet appareil à votre compte</h3>
+                <p>Vous êtes sur le point d'ajouter cet appareil à votre compte existant.</p>
+                <p>Cette action permettra à cet appareil d'accéder à vos données et processus.</p>
+                <p>Voulez-vous continuer ?</p>
+              </div>
+            `,
+            confirmText: 'Ajouter l\'appareil',
+            cancelText: 'Annuler'
+          }, true);
+
+          if (!result) {
+            console.log('User refused to add device');
+            await navigate('home');
+            return;
+          }
+
+          const myAddress = services.getDeviceAddress();
+          const updatedPairedAddresses = [...decodedAddresses, myAddress];
+          const updateProcessReturn = await services.updateProcess(pairingProcess!, {}, { pairedAddresses: updatedPairedAddresses }, null);
+          await services.handleApiReturn(updateProcessReturn);
+          // Now make the prd update and approve the change
+          const newStateId = updateProcessReturn.updated_process!.diffs[0].state_id;
+          console.debug(newStateId);
+          const prdUpdateReturn = await services.createPrdUpdate(addToId, newStateId);
+          await services.handleApiReturn(prdUpdateReturn);
+          const approveChangeReturn = await services.approveChange(addToId, newStateId); //Actually useless since this device is not a member of the process
+          await services.handleApiReturn(approveChangeReturn);
+          await navigate('account');
+          return;
+        } catch (e) {
+          console.error(e);
+          await navigate('home');
+        }
+      }
       await navigate('home');
     }
   } catch (error) {
@@ -781,6 +837,125 @@ export async function registerAllListeners() {
     }
   }
 
+  const handleGetMemberAddresses = async (event: MessageEvent) => {
+    if (event.data.type !== MessageType.GET_MEMBER_ADDRESSES) return;
+
+    try {
+      const { accessToken, processId } = event.data;
+
+      if (!accessToken || !(await tokenService.validateToken(accessToken, event.origin))) {
+        throw new Error('Invalid or expired session token');
+      }
+
+      const res = services.getAddressesForMemberId(processId);
+
+      window.parent.postMessage(
+        {
+          type: MessageType.MEMBER_ADDRESSES_RETRIEVED,
+          memberAddresses: res,
+          messageId: event.data.messageId
+        },
+        event.origin
+      );
+    } catch (e) {
+      const errorMsg = `Failed to get member addresses: ${e}`;
+      errorResponse(errorMsg, event.origin, event.data.messageId);
+    }
+  }
+
+  const handleAddDevice = async (event: MessageEvent) => {
+    if (event.data.type !== MessageType.ADD_DEVICE) return;
+
+    try {
+      const { accessToken } = event.data;
+
+      if (!accessToken || !(await tokenService.validateToken(accessToken, event.origin))) {
+        throw new Error('Invalid or expired session token');
+      }
+
+      // Get the current device address for the pairing URL
+      const myPairingProcessId = services.getPairingProcessId();
+      const currentUrl = window.location.origin;
+      const pairingUrl = `${currentUrl}?add_to_id=${myPairingProcessId}`;
+
+      // TODO get the current number of devices
+
+      const modalService = await ModalService.getInstance();
+      const result = await modalService.showConfirmationModal({
+        title: 'Ajout d\'un nouvel appareil',
+        content: `
+          <div class="modal-confirmation">
+            <h3>Ajouter un nouvel appareil</h3>
+            <p>Pour ajouter un nouvel appareil à votre compte, partagez l'URL suivante avec le nouvel appareil :</p>
+            <div style="margin: 15px 0; padding: 10px; background-color: #f5f5f5; border-radius: 4px; word-break: break-all; font-family: monospace; font-size: 12px;">
+              ${pairingUrl}
+            </div>
+            <p><small>Gardez cette URL secrète, elle permettra à l'appareil de se connecter à votre compte.</small></p>
+            <p>Ou scannez ce QR code avec le nouvel appareil :</p>
+            <div style="text-align: center; margin: 15px 0;">
+              <img src="https://api.qrserver.com/v1/create-qr-code/?size=200x200&data=${encodeURIComponent(pairingUrl)}" 
+                   alt="QR Code pour l'ajout d'appareil" 
+                   style="border: 1px solid #ddd; border-radius: 4px;">
+            </div>
+          </div>
+        `,
+        confirmText: 'Terminer',
+        cancelText: 'Annuler'
+      }, true);
+
+      if (!result) {
+        throw new Error('User cancelled device addition');
+      }
+
+      // Wait for the pairing process to be updated with the new device
+      const maxWaitTime = 300000; // 5 minutes
+      const pollInterval = 2000; // 2 seconds
+      const startTime = Date.now();
+      let deviceAdded = false;
+      
+      while (Date.now() - startTime < maxWaitTime && !deviceAdded) {
+        console.debug('Polling for device addition');
+        try {
+          const pairingProcess = await services.getProcess(myPairingProcessId);
+          if (pairingProcess) {
+            const uncommitedStates = services.getUncommitedStates(pairingProcess);
+            for (const state of uncommitedStates) {
+              const pairedAddresses = state.public_data['pairedAddresses'];
+              if (pairedAddresses) {
+                const decodedAddresses = services.decodeValue(pairedAddresses);
+                if (decodedAddresses.length > 1) {
+                  console.log('New device detected in pairing process');
+                  deviceAdded = true;
+                  break;
+                }
+              }
+            }
+          } else {
+            throw new Error('Process not found');
+          }
+        } catch (e) {
+          console.warn('Error while polling for device addition:', e);
+        }
+        
+        await new Promise(resolve => setTimeout(resolve, pollInterval));
+      }
+
+      window.parent.postMessage(
+        {
+          type: MessageType.DEVICE_ADDED,
+          pairingUrl: pairingUrl,
+          deviceAdded: deviceAdded,
+          messageId: event.data.messageId
+        },
+        event.origin
+      );
+
+    } catch (e) {
+      const errorMsg = `Failed to add device: ${e}`;
+      errorResponse(errorMsg, event.origin, event.data.messageId);
+    }
+  }
+
   window.removeEventListener('message', handleMessage);
   window.addEventListener('message', handleMessage);
 
@@ -832,6 +1007,12 @@ export async function registerAllListeners() {
         case MessageType.VALIDATE_MERKLE_PROOF:
           await handleValidateMerkleProof(event);
           break;
+        case MessageType.GET_MEMBER_ADDRESSES:
+          await handleGetMemberAddresses(event);
+          break;
+        case MessageType.ADD_DEVICE:
+          await handleAddDevice(event);
+          break;
         default:
           console.warn(`Unhandled message type: ${event.data.type}`);
       }