diff --git a/prism/src/jdd/JDDVars.java b/prism/src/jdd/JDDVars.java
index 8e2eb743..698166e8 100644
--- a/prism/src/jdd/JDDVars.java
+++ b/prism/src/jdd/JDDVars.java
@@ -68,7 +68,7 @@ public class JDDVars implements Iterable<JDDNode>
 		array = 0;
 		arrayBuilt = false;
 	}
-		
+
 	/**
 	 * Appends a variable to this JDDVars container.
 	 * <br>
@@ -92,6 +92,30 @@ public class JDDVars implements Iterable<JDDNode>
 		arrayBuilt = false;
 	}
 
+	/**
+	 * Creates a copy of this JDDVars container,
+	 * containing referenced copies of each variable JDDNode in this container.
+	 */
+	public JDDVars copy()
+	{
+		JDDVars result = new JDDVars();
+		for (JDDNode var : this) {
+			result.addVar(var.copy());
+		}
+		return result;
+	}
+
+	/**
+	 * Copies variables from another JDDVars container,
+	 * appending to this container.
+	 * Does a (referencing) copy of each of the variable JDDNodes.
+	 */
+	public void copyVarsFrom(JDDVars ddv) {
+		for (JDDNode var : ddv) {
+			addVar(var.copy());
+		}
+	}
+
 	/**
 	 * Removes the JDDNodes contained in ddv from this JDDVars container.
 	 * Does not decrease the refcount!