diff --git a/app/src/main/java/org/cutem/cutecalendar/model/TodoItem.java b/app/src/main/java/org/cutem/cutecalendar/model/TodoItem.java
index 74ec819..7df313e 100644
--- a/app/src/main/java/org/cutem/cutecalendar/model/TodoItem.java
+++ b/app/src/main/java/org/cutem/cutecalendar/model/TodoItem.java
@@ -98,15 +98,6 @@ public class TodoItem {
      */
     public static final String IMPORTANCE = "importance";
 
-    /**
-     * Value of a name of possible string-type property index.
-     *
-     * The corresponding value of stringProperties is formatted: "parent", "child".
-     *
-     * If the instance have no {@code COMPOSITE}, then the corresponding value should be assumed as "parent".
-     */
-    public static final String COMPOSITE = "composite";
-
     /**
      * Value of a name of possible string-type property index.
      * <p>
diff --git a/app/src/main/java/org/cutem/cutecalendar/model/TodoItemUtil.java b/app/src/main/java/org/cutem/cutecalendar/model/TodoItemUtil.java
index 30ab38c..e43a2ef 100644
--- a/app/src/main/java/org/cutem/cutecalendar/model/TodoItemUtil.java
+++ b/app/src/main/java/org/cutem/cutecalendar/model/TodoItemUtil.java
@@ -139,9 +139,9 @@ public class TodoItemUtil {
     public static boolean isIntersectedConflict(@NotNull TodoItem i1, @NotNull TodoItem i2) {
         int t1 = i1.getType();
         int t2 = i2.getType();
-        return isIntersected(i1, i2)
-                && arrayContains(INTERSECTED_CONFLICT, t1)
-                && arrayContains(INTERSECTED_CONFLICT, t2);
+        return arrayContains(INTERSECTED_CONFLICT, t1)
+                && arrayContains(INTERSECTED_CONFLICT, t2)
+                && isIntersected(i1, i2);
     }
 
 
@@ -232,33 +232,22 @@ public class TodoItemUtil {
     }
 
 
-    public static boolean isParentChildConflict(@NotNull TodoItem parent, @NotNull TodoItem child) {
+    public static boolean canBind(@NotNull TodoItem parent, @NotNull TodoItem child) {
         int pType = parent.getType();
         int cType = child.getType();
 
         return pType != cType && arrayContains(PARENT_CHILDREN_CONFLICT, pType)
-                && arrayContains(PARENT_CHILDREN_CONFLICT, cType);
+                && arrayContains(PARENT_CHILDREN_CONFLICT, cType)
+                && isIn(parent, child);
     }
 
-    public static boolean canBecomeSubTodoItem(@NotNull TodoItem parent, @NotNull TodoItem newItem) {
-        return isIn(parent, newItem) && !isParentChildConflict(parent, newItem);
-    }
-
-
-    public static boolean isParentTodoItem(@NotNull TodoItem item) {
-        return item.getStringProperty(CHILDREN_IDS) != null;
-    }
-
-    public static boolean isChildTodoItem(@NotNull TodoItem item) {
-        return item.getStringProperty(PARENT_ID) != null;
-    }
 
     public static List<Long> getAllChildrenIds(@NotNull TodoItem item) {
         String ids = item.getStringProperty(CHILDREN_IDS);
-        String[] idsSlice = ids.split("[;,]");
+        String[] idsSlice = ids == null ? new String[0] : ids.split("[;,]");
         ArrayList<Long> result = new ArrayList<>(idsSlice.length);
 
-        for (int i = 0; i < ids.length(); i++) {
+        for (int i = 0; i < result.size(); i++) {
             long id = Long.parseLong(idsSlice[i]);
             result.set(i, id);
         }
@@ -267,7 +256,7 @@ public class TodoItemUtil {
 
     public static long getParentId(@NotNull TodoItem item) {
         String id = item.getStringProperty(PARENT_ID);
-        return Long.parseLong(id);
+        return id == null ? item.getId() : Long.parseLong(id);
     }
 
     public static String idsToString(@NotNull Collection<Long> ids) {
@@ -277,21 +266,15 @@ public class TodoItemUtil {
         for (long i : ids) {
             if (!first) {
                 builder.append(';');
+            } else {
+                first = false;
             }
             builder.append(Long.toString(i));
-            first = false;
         }
         return builder.toString();
     }
 
     public static TodoItem[] bind(@NotNull TodoItem parent, @NotNull TodoItem child) {
-        if (!isParentTodoItem(parent)) {
-            throw new IllegalArgumentException("parent is not a parent todo-item");
-        }
-        if (!isChildTodoItem(child)) {
-            throw new IllegalArgumentException("child is not a child todo-item");
-        }
-
         TodoItemFactory fParent = new TodoItemFactory().copy(parent);
         TodoItemFactory fChild = new TodoItemFactory().copy(child);
 
@@ -301,26 +284,18 @@ public class TodoItemUtil {
 
         TodoItem newP = fParent
                 .stringProperties(CHILDREN_IDS, idsString)
-                .stringProperties(COMPOSITE, "parent")
                 .buildId(parent.getId());
 
         String pIdString = Long.toString(parent.getId());
 
         TodoItem newC = fChild
                 .stringProperties(PARENT_ID, pIdString)
-                .stringProperties(COMPOSITE, "child")
                 .buildId(child.getId());
 
         return new TodoItem[]{newP, newC};
     }
 
     public static TodoItem[] unbind(@NotNull TodoItem parent, @NotNull TodoItem child) {
-        if (!isParentTodoItem(parent)) {
-            throw new IllegalArgumentException("parent is not a parent todo-item");
-        }
-        if (!isChildTodoItem(child)) {
-            throw new IllegalArgumentException("child is not a child todo-item");
-        }
 
         TodoItemFactory fParent = new TodoItemFactory().copy(parent);
         TodoItemFactory fChild = new TodoItemFactory().copy(child);
@@ -331,18 +306,15 @@ public class TodoItemUtil {
 
         TodoItem newP = fParent
                 .stringProperties(CHILDREN_IDS, idsString)
-                .stringProperties(COMPOSITE, "parent")
                 .buildId(parent.getId());
 
         TodoItem newC = fChild
                 .stringProperties(PARENT_ID, null)
-                .stringProperties(COMPOSITE, "parent")
                 .buildId(child.getId());
 
         return new TodoItem[]{newP, newC};
     }
 
-
     public static TodoItem finishSingleTodoItem(@NotNull TodoItem item) {
         TodoItemFactory factory = new TodoItemFactory();
         return factory.copy(item).stringProperties(FINISH, "finish").buildId(item.getId());
@@ -350,7 +322,10 @@ public class TodoItemUtil {
 
     public static TodoItem finishTimelessItem(@NotNull String title) {
         TodoItemFactory factory = new TodoItemFactory();
-        return factory.wholeDay(Calendar.getInstance()).title(title).build();
+        return factory.wholeDay(Calendar.getInstance())
+                .title(title)
+                .stringProperties(FINISH, "finish")
+                .build();
     }
 
 }