diff --git a/src/core/jsonutil.cpp b/src/core/jsonutil.cpp
index ab4f86c..323854d 100644
--- a/src/core/jsonutil.cpp
+++ b/src/core/jsonutil.cpp
@@ -31,18 +31,24 @@ void JsonUtil::exportSellers(const fs::path& filePath, Marketplace* market)
     writer->write(root, &file);
 }
 
-void JsonUtil::importSellers(const fs::path& filePath, Marketplace* market)
+void JsonUtil::importSellers(const fs::path& filePath, Marketplace* market, bool cleanup)
 {
-    for (auto& seller : market->getSellers()) {
-        seller->setState(Seller::State::DELETE);
+    if (cleanup) {
+        for (auto& seller : market->getSellers()) {
+            seller->setState(Seller::State::DELETE);
+        }
+        market->storeToDb(true);
     }
-    market->storeToDb(true);
 
     Json::Value jsonValues;
     std::ifstream file(filePath);
     file >> jsonValues;
 
     for (auto val : jsonValues["sellers"]) {
+        auto sellerExist = market->findSellerWithUuid(val["uuid"].asString());
+        if (sellerExist) {
+            continue;
+        }
         auto seller = std::make_unique<Seller>();
         seller->setUuidFromString(val["uuid"].asString());
         seller->setSellerNo(val["seller_no"].asInt());
@@ -80,6 +86,17 @@ void JsonUtil::exportSales(const fs::path& filePath, Marketplace* market, int ca
 
     std::unique_ptr<Json::StreamWriter> writer(builder.newStreamWriter());
 
+    // Do export sellers (maybe there are new sellers created during sale)
+    for (const auto& seller : market->getSellers()) {
+        Json::Value newEntry;
+        newEntry["uuid"] = seller->getUuidAsString();
+        newEntry["seller_no"] = seller->getSellerNo();
+        newEntry["last_name"] = seller->getLastName();
+        newEntry["first_name"] = seller->getFirstName();
+        newEntry["num_offered_articles"] = seller->numArticlesOffered();
+        root["sellers"].append(newEntry);
+    }
+
     root["source_no"] = cashPointNo;
 
     for (const auto& sale : market->getSales()) {
@@ -110,6 +127,9 @@ void JsonUtil::exportSales(const fs::path& filePath, Marketplace* market, int ca
 
 void JsonUtil::importSales(const fs::path& filePath, Marketplace* market, int cashPointNo)
 {
+    // First import newly created sellers during the sale phase
+    importSellers(filePath, market, false);
+
     Json::Value jsonValues;
     std::ifstream file(filePath);
     file >> jsonValues;
diff --git a/src/core/jsonutil.h b/src/core/jsonutil.h
index 3663dcc..43d8745 100644
--- a/src/core/jsonutil.h
+++ b/src/core/jsonutil.h
@@ -10,7 +10,7 @@ class JsonUtil
 {
   public:
     static void exportSellers(const std::filesystem::path& filePath, Marketplace* market);
-    static void importSellers(const std::filesystem::path& filePath, Marketplace* market);
+    static void importSellers(const std::filesystem::path& filePath, Marketplace* market, bool cleanup = true);
     static void exportSales(const std::filesystem::path& filePath, Marketplace* market, int cashPointNo);
     static void importSales(const std::filesystem::path& filePath, Marketplace* market, int cashPointNo);
 };
diff --git a/src/gui/sellerdialog.cpp b/src/gui/sellerdialog.cpp
index 1c4ef97..0b375ff 100644
--- a/src/gui/sellerdialog.cpp
+++ b/src/gui/sellerdialog.cpp
@@ -25,14 +25,14 @@ SellerDialog::SellerDialog(QWidget* parent, Qt::WindowFlags f) : QDialog(parent,
 void SellerDialog::on_newButton_clicked()
 {
     // Don't allow new seller if market has already started
-    if (market_->getSales().size() > 0) {
+    /* if (market_->getSales().size() > 0) {
         QMessageBox(QMessageBox::Icon::Warning, "Hinweis",
                     "Da die Verkaufsphase schon begonnen hat (Artikel wurden bereits verkauft) "
                     "können Sie keine Verkäufer mehr hinzufügen.",
                     QMessageBox::StandardButton::Ok, this)
             .exec();
         return;
-    }
+    } */
 
     ui_.tableView->reset();
     ui_.tableView->model()->insertRows(ui_.tableView->model()->rowCount(), 1);