diff --git a/src/lang/english.txt b/src/lang/english.txt
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -3297,7 +3297,7 @@ STR_GROUP_DEFAULT_ROAD_VEHICLES         
 STR_GROUP_DEFAULT_SHIPS                                         :Ungrouped ships
 STR_GROUP_DEFAULT_AIRCRAFTS                                     :Ungrouped aircraft
 
-STR_GROUPS_CLICK_ON_GROUP_FOR_TOOLTIP                           :{BLACK}Groups - click on a group to list all vehicles of this group
+STR_GROUPS_CLICK_ON_GROUP_FOR_TOOLTIP                           :{BLACK}Groups - click on a group to list all vehicles of this group. Drag and drop groups to arrange hierarchy.
 STR_GROUP_CREATE_TOOLTIP                                        :{BLACK}Click to create a group
 STR_GROUP_DELETE_TOOLTIP                                        :{BLACK}Delete the selected group
 STR_GROUP_RENAME_TOOLTIP                                        :{BLACK}Rename the selected group
@@ -4276,6 +4276,7 @@ STR_ERROR_YOU_ALREADY_OWN_IT            
 STR_ERROR_GROUP_CAN_T_CREATE                                    :{WHITE}Can't create group...
 STR_ERROR_GROUP_CAN_T_DELETE                                    :{WHITE}Can't delete this group...
 STR_ERROR_GROUP_CAN_T_RENAME                                    :{WHITE}Can't rename group...
+STR_ERROR_GROUP_CAN_T_SET_PARENT                                :{WHITE}Can't set parent group...
 STR_ERROR_GROUP_CAN_T_REMOVE_ALL_VEHICLES                       :{WHITE}Can't remove all vehicles from this group...
 STR_ERROR_GROUP_CAN_T_ADD_VEHICLE                               :{WHITE}Can't add the vehicle to this group...
 STR_ERROR_GROUP_CAN_T_ADD_SHARED_VEHICLE                        :{WHITE}Can't add shared vehicles to group...