diff --git a/content/treestyletab/config.xul b/content/treestyletab/config.xul
index 8d68c497..a5d34635 100644
--- a/content/treestyletab/config.xul
+++ b/content/treestyletab/config.xul
@@ -275,6 +275,9 @@
 		<preference id="extensions.treestyletab.openGroupBookmarkAsTabSubTree"
 			name="extensions.treestyletab.openGroupBookmarkAsTabSubTree"
 			type="bool"/>
+		<preference id="extensions.treestyletab.openGroupBookmarkAsTabSubTree.underParent"
+			name="extensions.treestyletab.openGroupBookmarkAsTabSubTree.underParent"
+			type="bool"/>
 		<preference id="browser.tabs.loadFolderAndReplace"
 			name="browser.tabs.loadFolderAndReplace.override"
 			type="bool"/>
@@ -337,7 +340,12 @@
 					<radiogroup id="openGroupBookmarkAsTabSubTree-radiogroup"
 						orient="vertical"
 						oncommand="onChangeGroupBookmarkRadio();">
-						<radio value="subtree" label="&config.openGroupBookmarkAsTabSubTree.subtree;"/>
+						<hbox align="center">
+							<radio value="subtree" label="&config.openGroupBookmarkAsTabSubTree.subtree;"/>
+							<checkbox id="openGroupBookmarkAsTabSubTree.underParent-check"
+								label="&config.openGroupBookmarkAsTabSubTree.underParent;"
+								preference="extensions.treestyletab.openGroupBookmarkAsTabSubTree.underParent"/>
+						</hbox>
 						<radio value="flat"    label="&config.openGroupBookmarkAsTabSubTree.flat;"/>
 						<radio value="replace" label="&config.openGroupBookmarkAsTabSubTree.replace;"
 							label-fx2="&config.openGroupBookmarkAsTabSubTree.replace.fx2;"/>
diff --git a/locale/de-DE/treestyletab/treestyletab.dtd b/locale/de-DE/treestyletab/treestyletab.dtd
index 5253c954..21bb933e 100644
--- a/locale/de-DE/treestyletab/treestyletab.dtd
+++ b/locale/de-DE/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "Als eigenständige Tabs öffnen">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "Replace the current one tab to the pages in the folder (Firefox default)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "Die Seiten im Lesezeichenverzeichnis in existierende Tabs laden (Firefox Standard)">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "Neue Tabs statt neue Fenster öffnen">
 
diff --git a/locale/en-US/treestyletab/treestyletab.dtd b/locale/en-US/treestyletab/treestyletab.dtd
index 21a4725e..bb7157f0 100644
--- a/locale/en-US/treestyletab/treestyletab.dtd
+++ b/locale/en-US/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "Open as separate tabs">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "Replace the current one tab to the pages in the folder (Firefox default)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "Replace all tabs to the pages in the folder (Firefox default)">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "Open tabs instead of windows">
 
diff --git a/locale/es-ES/treestyletab/treestyletab.dtd b/locale/es-ES/treestyletab/treestyletab.dtd
index ac8bfd64..331068d0 100644
--- a/locale/es-ES/treestyletab/treestyletab.dtd
+++ b/locale/es-ES/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "Abrir como pestañas separadas">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "Replace the current one tab to the pages in the folder (Firefox default)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "Remplazar todas las pestañas con las páginas en la carpeta (Predeterminado en Firefox)">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "Abrir pestañas en vez de ventanas">
 
diff --git a/locale/it-IT/treestyletab/treestyletab.dtd b/locale/it-IT/treestyletab/treestyletab.dtd
index 01776c2e..82748178 100644
--- a/locale/it-IT/treestyletab/treestyletab.dtd
+++ b/locale/it-IT/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "apre i segnalibri in schede separate">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "sostituisce la scheda in uso con i segnalibri contenuti nella cartella selezionata (comportamento predefinito di Firefox)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "sostituisce la scheda in uso con i segnalibri contenuti nella cartella selezionata (comportamento predefinito di Firefox)">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "Finestre">
 
diff --git a/locale/ja/treestyletab/treestyletab.dtd b/locale/ja/treestyletab/treestyletab.dtd
index 9daa55bf..21e5f614 100644
--- a/locale/ja/treestyletab/treestyletab.dtd
+++ b/locale/ja/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "ばらばらのタブとして開く">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "現在のタブ1つだけをブックマークの内容で置き換える（Firefox初期状態）">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "現在開いているすべてのタブをブックマークの内容で置き換える（Firefox初期状態）">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "グループ化用のダミーのタブを親にする">
 
 <!ENTITY config.tabs.restriction.tab "ウィンドウの代わりにタブを開く">
 
diff --git a/locale/pl-PL/treestyletab/treestyletab.dtd b/locale/pl-PL/treestyletab/treestyletab.dtd
index d3fe839e..32883e7d 100644
--- a/locale/pl-PL/treestyletab/treestyletab.dtd
+++ b/locale/pl-PL/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "Otwieraj jako osobne karty">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "Replace the current one tab to the pages in the folder (Firefox default)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "Zastąp wszystkie karty stronami z folderu (domyślnie działanie Firefoksa)">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "Otwieranie kart zamiast okien">
 
diff --git a/locale/ru-RU/treestyletab/treestyletab.dtd b/locale/ru-RU/treestyletab/treestyletab.dtd
index 60344af8..0e4e3346 100755
--- a/locale/ru-RU/treestyletab/treestyletab.dtd
+++ b/locale/ru-RU/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "Открывать как раздельные вкладки">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "Replace the current one tab to the pages in the folder (Firefox default)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "Заменить все вкладки страницами из папки (в Firefox по умолчанию)">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "Открытие вкладок вместо окон">
 
diff --git a/locale/zh-CN/treestyletab/treestyletab.dtd b/locale/zh-CN/treestyletab/treestyletab.dtd
index b9aedf2f..88998a9d 100644
--- a/locale/zh-CN/treestyletab/treestyletab.dtd
+++ b/locale/zh-CN/treestyletab/treestyletab.dtd
@@ -63,6 +63,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "在单独标签中打开">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "Replace the current one tab to the pages in the folder (Firefox default)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "将文件夹中所有标签置换为页面 (Firefox 默认)">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "打开标签而非窗口">
 
diff --git a/locale/zh-TW/treestyletab/treestyletab.dtd b/locale/zh-TW/treestyletab/treestyletab.dtd
index 72a5e7e0..e7fac15f 100644
--- a/locale/zh-TW/treestyletab/treestyletab.dtd
+++ b/locale/zh-TW/treestyletab/treestyletab.dtd
@@ -61,6 +61,7 @@
 <!ENTITY config.openGroupBookmarkAsTabSubTree.flat    "用分開的分頁開啟">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace "Replace the current one tab to the pages in the folder (Firefox default)">
 <!ENTITY config.openGroupBookmarkAsTabSubTree.replace.fx2 "將所有目前開啟的分頁取代為書籤的內容（Firefox 預設）">
+<!ENTITY config.openGroupBookmarkAsTabSubTree.underParent "Put tabs under a dummy tab for grouping">
 
 <!ENTITY config.tabs.restriction.tab "開啟分頁代替視窗">
 <!ENTITY config.open_newwindow.caption "從網頁鏈結開啟新視窗的控制">