diff --git a/src/utils/ufd.c b/src/utils/ufd.c
index 9cf1af3..ed9f0c6 100644
--- a/src/utils/ufd.c
+++ b/src/utils/ufd.c
@@ -5,10 +5,10 @@
 
 void ufd__init(struct ufd_t* ufd, struct context_entry_t* thread)
 {
+    TAILQ_INIT(&ufd->children);
     ufd->thread = thread;
     ufd->repr = ufd,
     ufd->parent = NULL;
-    ufd->child = NULL;
 }
 
 
@@ -21,6 +21,7 @@ void ufd__join(struct ufd_t* th1, struct ufd_t* th2)
     {
         a->parent = th2;
         a->repr = b;
+        TAILQ_INSERT_TAIL(&a->repr->children, a, link);
     }
 }
 
@@ -38,9 +39,10 @@ struct ufd_t* ufd__find(struct ufd_t* th)
 
 void ufd__delete(struct ufd_t* th)
 {
-    if (th->child != NULL)
-    {
-        th->child->parent = th->child;
-        th->child->repr = th->child;
+    struct ufd_t* child;
+
+    TAILQ_FOREACH(child, &th->children, link) {
+        child->parent = NULL;
+        child->repr = child;
     }
 }
diff --git a/src/utils/ufd.h b/src/utils/ufd.h
index b7b0522..9ba2d38 100644
--- a/src/utils/ufd.h
+++ b/src/utils/ufd.h
@@ -2,15 +2,20 @@
 #define _UNION_FIND_H_
 #include <sys/queue.h>
 
+TAILQ_HEAD(ufd_children_t, ufd_t);
+
 // union find delete data structure
 struct ufd_t {
     struct ufd_t* parent;
     struct ufd_t* repr;
-    struct ufd_t* child;
     struct context_entry_t* thread;
+    struct ufd_children_t children;
+    TAILQ_ENTRY(ufd_t) link;
 };
 
 
+struct ufd_t ufd__make_set(struct context_entry_t* thread);
+
 void ufd__init(struct ufd_t* ufd, struct context_entry_t* thread);
 
 /*