diff --git a/src/Singleton/IRegistry.php b/src/Singleton/IRegistry.php
index 212fa0e..6bf4b7a 100644
--- a/src/Singleton/IRegistry.php
+++ b/src/Singleton/IRegistry.php
@@ -12,36 +12,27 @@ use Throwable;
  */
 interface IRegistry {
     /**
-     * Register a new entry
+     * Get the instance
      *
-     * @param string $name The entry name
-     * @param array  $args The instance constructor arguments
+     * If the instance is not already created then create it
      *
-     * @return void
+     * @param string|null $name The entry name. Null if default entry name
      *
-     * @throws InvalidArgumentException If the entry name already exists
+     * @return static The instance
+     *
+     * @throws InvalidArgumentException If the entry name doesn't exist
+     * @throws Throwable If instantiating failed
      */
-    public static function addEntry (string $name, ...$args): void;
+    public static function getInstance (?string $name = null): self;
+
     /**
      * Check if an entry name already exists
      *
      * @param string $name The entry name
      *
      * @return bool TRUE if the entry name already exists
-     */
-    public static function hasEntry (string $name): bool;
-
-    /**
-     * Get the instance
-     *
-     * If the instance is not already created then create it
-     *
-     * @param string The entry name
      *
-     * @return static The instance
-     *
-     * @throws InvalidArgumentException If the entry name doesn't exist
-     * @throws Throwable If instantiating failed
+     * @throws Throwable If an error occur
      */
-    public static function getInstance (string $name): self;
+    public static function hasEntry (string $name): bool;
 }
\ No newline at end of file
diff --git a/src/Singleton/IRegistryDefault.php b/src/Singleton/IRegistryDefault.php
deleted file mode 100644
index 60b8e59..0000000
--- a/src/Singleton/IRegistryDefault.php
+++ /dev/null
@@ -1,40 +0,0 @@
-<?php
-
-namespace jrosset\Singleton;
-
-use InvalidArgumentException;
-use Throwable;
-
-/**
- * Interface for class implementing an instance register with a default entry name
- */
-interface IRegistryDefault extends IRegistry {
-    /**
-     * The default entry name
-     *
-     * @return string The default entry name
-     *
-     * @throws InvalidArgumentException If the entry name isn't set
-     */
-    public static function getDefaultEntryName (): string;
-    /**
-     * Set the default entry name
-     *
-     * <b>WARNING :</b> The entry name MUST already exists
-     *
-     * @param string $name The new default name
-     *
-     * @return void
-     *
-     * @throws InvalidArgumentException If the entry name doesn't exists
-     */
-    public static function setDefaultEntryName (string $name): void;
-
-    /**
-     * @inheritDoc
-     *
-     * @throws InvalidArgumentException If the entry name doesn't exist or no default entry name
-     * @throws Throwable If instantiating failed
-     */
-    public static function getInstance (?string $name = null): self;
-}
\ No newline at end of file
diff --git a/src/Singleton/TRegistry.php b/src/Singleton/TRegistry.php
index 22c327d..3f66ce6 100644
--- a/src/Singleton/TRegistry.php
+++ b/src/Singleton/TRegistry.php
@@ -2,6 +2,9 @@
 
 namespace jrosset\Singleton;
 
+use InvalidArgumentException;
+use Throwable;
+
 /**
  * Default implementation for registry
  *
@@ -10,12 +13,75 @@ namespace jrosset\Singleton;
  * @see IRegistry for interface
  */
 trait TRegistry {
-    use TRegistryBase;
+    /**
+     * @var array[] The registry entries
+     */
+    private static array $registerEntries = [];
+    /**
+     * @var static[] The current instances
+     */
+    private static array $registryInstances = [];
+
+    /**
+     * Initialize registry entries
+     *
+     * Use {@see TRegistryBase::addEntry()} to add a new entry
+     *
+     * @return void
+     *
+     * @throws Throwable If an error occur
+     */
+    protected static abstract function initializeEntries (): void;
+    /**
+     * Register a new entry
+     *
+     * @param string $name The entry name
+     * @param array  $args The instance constructor arguments
+     *
+     * @return void
+     *
+     * @throws InvalidArgumentException If the entry name already exists
+     * @throws Throwable If an error occur
+     */
+    protected static function addEntry (string $name, ...$args): void {
+        if (static::hasEntry($name)) {
+            throw new InvalidArgumentException('An entry with "' . $name . '" already exists');
+        }
+        static::$registerEntries[$name] = $args;
+    }
+
+    /**
+     * The default entry name
+     *
+     * @return string The default entry name
+     *
+     * @throws InvalidArgumentException If the entry name isn't set
+     */
+    protected static function getDefaultEntryName (): string {
+        throw new InvalidArgumentException('No default entry name available');
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public static function hasEntry (string $name): bool {
+        if (count(static::$registerEntries[$name] ?? []) === 0) {
+            static::initializeEntries();
+        }
+        return isset(static::$registerEntries[$name]);
+    }
 
     /**
      * @inheritDoc
      */
-    public static function getInstance (string $name): self {
-        return static::TRegistryBase_getInstance($name);
+    public static function getInstance (?string $name = null): self {
+        $name ??= static::getDefaultEntryName();
+        if (!static::hasEntry($name)) {
+            throw new InvalidArgumentException('Unable to find entry "' . $name . '"');
+        }
+        if (!isset(static::$registryInstances[$name])) {
+            static::$registryInstances[$name] = new static(...static::$registerEntries[$name]);
+        }
+        return static::$registryInstances[$name];
     }
 }
\ No newline at end of file
diff --git a/src/Singleton/TRegistryBase.php b/src/Singleton/TRegistryBase.php
deleted file mode 100644
index 40c4656..0000000
--- a/src/Singleton/TRegistryBase.php
+++ /dev/null
@@ -1,62 +0,0 @@
-<?php
-
-namespace jrosset\Singleton;
-
-use InvalidArgumentException;
-use Throwable;
-
-/**
- * Default base implementation for registry
- *
- * Instance initialization through the constructor
- *
- * @see IRegistry for interface
- */
-trait TRegistryBase {
-    /**
-     * @var array[] The registry entries
-     */
-    private static array $registerEntries = [];
-    /**
-     * @var static[] The current instances
-     */
-    private static array $registryInstances = [];
-
-    /**
-     * @inheritDoc
-     */
-    public static function addEntry (string $name, ...$args): void {
-        if (static::hasEntry($name)) {
-            throw new InvalidArgumentException('An entry with "' . $name . '" already exists');
-        }
-        static::$registerEntries[$name] = $args;
-    }
-    /**
-     * @inheritDoc
-     */
-    public static function hasEntry (string $name): bool {
-        return isset(static::$registerEntries[$name]);
-    }
-
-    /**
-     * Get the instance
-     *
-     * If the instance is not already created then create it
-     *
-     * @param string The entry name
-     *
-     * @return static The instance
-     *
-     * @throws InvalidArgumentException If the entry name doesn't exist
-     * @throws Throwable If instantiating failed
-     */
-    public static function TRegistryBase_getInstance (string $name): self {
-        if (!static::hasEntry($name)) {
-            throw new InvalidArgumentException('Unable to find entry "' . $name . '"');
-        }
-        if (!isset(static::$registryInstances[$name])) {
-            static::$registryInstances[$name] = new static(...static::$registerEntries[$name]);
-        }
-        return static::$registryInstances[$name];
-    }
-}
\ No newline at end of file
diff --git a/src/Singleton/TRegistryDefault.php b/src/Singleton/TRegistryDefaultEntryName.php
similarity index 63%
rename from src/Singleton/TRegistryDefault.php
rename to src/Singleton/TRegistryDefaultEntryName.php
index d4f1cda..6730704 100644
--- a/src/Singleton/TRegistryDefault.php
+++ b/src/Singleton/TRegistryDefaultEntryName.php
@@ -11,16 +11,18 @@ use InvalidArgumentException;
  *
  * @see IRegistryDefault for interface
  */
-trait TRegistryDefault {
-    use TRegistryBase;
-
+trait TRegistryDefaultEntryName {
     /**
      * @var string|null The default entry name. NULL if not defined yet
      */
     private static ?string $registryDefaultEntryName = null;
 
     /**
-     * @inheritDoc
+     * The default entry name
+     *
+     * @return string The default entry name
+     *
+     * @throws InvalidArgumentException If the entry name isn't set
      */
     public static function getDefaultEntryName (): string {
         if (static::$registryDefaultEntryName === null) {
@@ -29,16 +31,17 @@ trait TRegistryDefault {
         return static::$registryDefaultEntryName;
     }
     /**
-     * @inheritDoc
+     * Set the default entry name
+     *
+     * <b>WARNING :</b> The entry name MUST already exists
+     *
+     * @param string $name The new default name
+     *
+     * @return void
+     *
+     * @throws InvalidArgumentException If the entry name doesn't exists
      */
     public static function setDefaultEntryName (string $name): void {
         static::$registryDefaultEntryName = $name;
     }
-
-    /**
-     * @inheritDoc
-     */
-    public static function getInstance (?string $name = null): self {
-        return static::TRegistryBase_getInstance($name ?? static::getDefaultEntryName());
-    }
 }
\ No newline at end of file
diff --git a/src/Singleton/TRegistryExternal.php b/src/Singleton/TRegistryExternal.php
new file mode 100644
index 0000000..d07339f
--- /dev/null
+++ b/src/Singleton/TRegistryExternal.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace jrosset\Singleton;
+
+/**
+ * Default implementation for registry with external added entries
+ *
+ * Instance initialization through the constructor
+ *
+ * @see IRegistry for interface
+ */
+trait TRegistryExternal {
+    use TRegistry {
+        addEntry as protected TRegistry_addEntry;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public static function addEntry (string $name, ...$args): void {
+        self::TRegistry_addEntry($name, ...$args);
+    }
+    /**
+     * @inheritDoc
+     */
+    protected static function initializeEntries (): void {
+        // Do nothing : add entry is now public for external added entries
+    }
+}
\ No newline at end of file
diff --git a/tests/registry.php b/tests/registry.php
index f1fe1e8..a2392d8 100644
--- a/tests/registry.php
+++ b/tests/registry.php
@@ -4,12 +4,12 @@
 /** @noinspection PhpIllegalPsrClassPathInspection */
 
 use jrosset\Singleton\IRegistry;
-use jrosset\Singleton\TRegistry;
+use jrosset\Singleton\TRegistryExternal;
 
 require_once __DIR__ . '/../vendor/autoload.php';
 
 class RegistryTest implements IRegistry {
-    use TRegistry;
+    use TRegistryExternal;
 
     private int $cpt;
 
diff --git a/tests/registry_default.php b/tests/registry_default.php
index c93eec1..c120ff8 100644
--- a/tests/registry_default.php
+++ b/tests/registry_default.php
@@ -3,13 +3,16 @@
 
 /** @noinspection PhpIllegalPsrClassPathInspection */
 
-use jrosset\Singleton\IRegistryDefault;
-use jrosset\Singleton\TRegistryDefault;
+use jrosset\Singleton\IRegistry;
+use jrosset\Singleton\TRegistryDefaultEntryName;
+use jrosset\Singleton\TRegistryExternal;
 
 require_once __DIR__ . '/../vendor/autoload.php';
 
-class RegistryDefaultTest implements IRegistryDefault {
-    use TRegistryDefault;
+class RegistryDefaultTest implements IRegistry {
+    use TRegistryExternal, TRegistryDefaultEntryName {
+        TRegistryDefaultEntryName::getDefaultEntryName insteadof TRegistryExternal;
+    }
 
     private int $cpt;