diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/IOrderLineGroup.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/IOrderLineGroup.java
index 19b7e9ebf..8bd284a54 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/IOrderLineGroup.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/IOrderLineGroup.java
@@ -20,23 +20,13 @@
 
 package org.navalplanner.business.orders.entities;
 
+import org.navalplanner.business.trees.ITreeNode;
+
 /**
  * Container of {@link OrderElement}. <br />
  *
  * @author Óscar González Fernández <ogonzalez@igalia.com>
  */
-public interface IOrderLineGroup {
+public interface IOrderLineGroup extends ITreeNode<OrderElement> {
 
-    public void add(OrderElement orderElement);
-
-    public void remove(OrderElement orderElement);
-
-    public void replace(OrderElement oldOrderElement,
-            OrderElement newOrderElement);
-
-    public void up(OrderElement orderElement);
-
-    public void down(OrderElement orderElement);
-
-    public void add(int position, OrderElement orderElement);
 }
\ No newline at end of file
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderLineGroupManipulator.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderLineGroupManipulator.java
index 2df6f266a..266db0b7b 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderLineGroupManipulator.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderLineGroupManipulator.java
@@ -20,15 +20,16 @@
 
 package org.navalplanner.business.orders.entities;
 
-import java.util.Collections;
 import java.util.List;
 
+import org.navalplanner.business.trees.TreeNodeOnList;
 
 /**
  * Implementation of {@link IOrderLineGroup}. <br />
  * @author Óscar González Fernández <ogonzalez@igalia.com>
  */
-public class OrderLineGroupManipulator implements IOrderLineGroup {
+public class OrderLineGroupManipulator extends
+        TreeNodeOnList<OrderElement, OrderLineGroup> {
 
     public static OrderLineGroupManipulator createManipulatorForOrder(
             List<OrderElement> orderElements) {
@@ -40,79 +41,40 @@ public class OrderLineGroupManipulator implements IOrderLineGroup {
         return new OrderLineGroupManipulator(group, children);
     }
 
-    private final List<OrderElement> orderElements;
-    private final OrderLineGroup parent;
-
     private OrderLineGroupManipulator(OrderLineGroup parent,
             List<OrderElement> orderElements) {
-        this.parent = parent;
-        this.orderElements = orderElements;
+        super(parent, orderElements);
+    }
+
+    protected void setParentIfRequired(OrderElement orderElement) {
+        if (getParent() != null) {
+            orderElement.setParent(getParent());
+        }
     }
 
     @Override
-    public void add(OrderElement orderElement) {
-        setParentIfRequired(orderElement);
-        orderElements.add(orderElement);
-        addSchedulingStateToParent(orderElement);
-    }
-
-    private void setParentIfRequired(OrderElement orderElement) {
-        if (this.parent != null) {
-            orderElement.setParent(this.parent);
-        }
+    protected void onChildAdded(OrderElement newChild) {
+        addSchedulingStateToParent(newChild);
     }
 
     private void addSchedulingStateToParent(OrderElement orderElement) {
-        if (this.parent != null) {
+        final OrderLineGroup parent = getParent();
+        if (parent != null) {
             SchedulingState schedulingState = orderElement.getSchedulingState();
             removeSchedulingStateFromParent(orderElement);
-            this.parent.getSchedulingState().add(schedulingState);
+            parent.getSchedulingState().add(schedulingState);
         }
     }
 
+    @Override
+    protected void onChildRemoved(OrderElement previousChild) {
+        removeSchedulingStateFromParent(previousChild);
+    }
+
     private void removeSchedulingStateFromParent(OrderElement orderElement) {
         SchedulingState schedulingState = orderElement.getSchedulingState();
         if (!schedulingState.isRoot()) {
             schedulingState.getParent().removeChild(schedulingState);
         }
     }
-
-    @Override
-    public void remove(OrderElement orderElement) {
-        orderElements.remove(orderElement);
-        removeSchedulingStateFromParent(orderElement);
-    }
-
-    @Override
-    public void replace(OrderElement oldOrderElement, OrderElement orderElement) {
-        setParentIfRequired(orderElement);
-        Collections.replaceAll(orderElements, oldOrderElement, orderElement);
-        addSchedulingStateToParent(orderElement);
-    }
-
-    @Override
-    public void down(OrderElement orderElement) {
-        int position = orderElements.indexOf(orderElement);
-        if (position < orderElements.size() - 1) {
-            orderElements.remove(position);
-            orderElements.add(position + 1, orderElement);
-        }
-    }
-
-    @Override
-    public void up(OrderElement orderElement) {
-        int position = orderElements.indexOf(orderElement);
-        if (position > 0) {
-            orderElements.remove(position);
-            orderElements.add(position - 1, orderElement);
-        }
-    }
-
-    @Override
-    public void add(int position, OrderElement orderElement) {
-        setParentIfRequired(orderElement);
-        orderElements.add(position, orderElement);
-        addSchedulingStateToParent(orderElement);
-    }
-
-}
+}
\ No newline at end of file
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/trees/ITreeNode.java b/navalplanner-business/src/main/java/org/navalplanner/business/trees/ITreeNode.java
new file mode 100644
index 000000000..d4ca373a8
--- /dev/null
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/trees/ITreeNode.java
@@ -0,0 +1,41 @@
+/*
+ * This file is part of ###PROJECT_NAME###
+ *
+ * Copyright (C) 2009 Fundación para o Fomento da Calidade Industrial e
+ *                    Desenvolvemento Tecnolóxico de Galicia
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.navalplanner.business.trees;
+
+
+/**
+ * Represents an entity that can work as a node at a tree<br />
+ * @author Óscar González Fernández <ogonzalez@igalia.com>
+ */
+public interface ITreeNode<T> {
+
+    public void add(T newChild);
+
+    public void remove(T existentChild);
+
+    public void replace(T previousChild, T newChild);
+
+    public void up(T existentChild);
+
+    public void down(T existentChild);
+
+    public void add(int position, T newChild);
+
+}
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/trees/TreeNodeOnList.java b/navalplanner-business/src/main/java/org/navalplanner/business/trees/TreeNodeOnList.java
new file mode 100644
index 000000000..e1e479b90
--- /dev/null
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/trees/TreeNodeOnList.java
@@ -0,0 +1,95 @@
+/*
+ * This file is part of ###PROJECT_NAME###
+ *
+ * Copyright (C) 2009 Fundación para o Fomento da Calidade Industrial e
+ *                    Desenvolvemento Tecnolóxico de Galicia
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.navalplanner.business.trees;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Implementation of {@link ITreeNode} that mutates a list <br />
+ * @author Óscar González Fernández <ogonzalez@igalia.com>
+ */
+public abstract class TreeNodeOnList<T, P> implements ITreeNode<T> {
+
+    private final List<T> children;
+    private final P parent;
+
+    protected TreeNodeOnList(P parent, List<T> children) {
+        this.parent = parent;
+        this.children = children;
+    }
+
+    @Override
+    public void add(T newChild) {
+        setParentIfRequired(newChild);
+        children.add(newChild);
+        onChildAdded(newChild);
+    }
+
+    protected P getParent() {
+        return parent;
+    }
+
+    protected abstract void setParentIfRequired(T newChild);
+
+    protected abstract void onChildAdded(T newChild);
+
+    protected abstract void onChildRemoved(T previousChild);
+
+    @Override
+    public void remove(T previousChild) {
+        children.remove(previousChild);
+        onChildRemoved(previousChild);
+    }
+
+    @Override
+    public void replace(T previousChild, T newChild) {
+        setParentIfRequired(newChild);
+        Collections.replaceAll(children, previousChild, newChild);
+        onChildAdded(newChild);
+        onChildRemoved(previousChild);
+    }
+
+    @Override
+    public void down(T existentChild) {
+        int position = children.indexOf(existentChild);
+        if (position < children.size() - 1) {
+            children.remove(position);
+            children.add(position + 1, existentChild);
+        }
+    }
+
+    @Override
+    public void up(T existentChild) {
+        int position = children.indexOf(existentChild);
+        if (position > 0) {
+            children.remove(position);
+            children.add(position - 1, existentChild);
+        }
+    }
+
+    @Override
+    public void add(int position, T newChild) {
+        setParentIfRequired(newChild);
+        children.add(position, newChild);
+        onChildAdded(newChild);
+    }
+
+}