This worked for me;
use master
go
-- FORUM_FORUM
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_FORUM] ON
INSERT INTO [destination_db].[dbo].[FORUM_FORUM]([CAT_ID], [FORUM_ID], [F_STATUS], [F_MAIL], [F_SUBJECT], [F_URL], [F_DESCRIPTION], [F_TOPICS], [F_COUNT], [F_LAST_POST], [F_PASSWORD_NEW], [F_PRIVATEFORUMS], [F_TYPE], [F_IP], [F_LAST_POST_AUTHOR], [F_LAST_POST_TOPIC_ID], [F_LAST_POST_REPLY_ID], [F_A_TOPICS], [F_A_COUNT], [F_DEFAULTDAYS], [F_COUNT_M_POSTS], [F_MODERATION], [F_SUBSCRIPTION], [F_ORDER], [F_L_ARCHIVE], [F_ARCHIVE_SCHED], [F_L_DELETE], [F_DELETE_SCHED], [F_POLLS])
SELECT [CAT_ID], [FORUM_ID], [F_STATUS], [F_MAIL], [F_SUBJECT], [F_URL], [F_DESCRIPTION], [F_TOPICS], [F_COUNT], [F_LAST_POST], [F_PASSWORD_NEW], [F_PRIVATEFORUMS], [F_TYPE], [F_IP], [F_LAST_POST_AUTHOR], [F_LAST_POST_TOPIC_ID], [F_LAST_POST_REPLY_ID], [F_A_TOPICS], [F_A_COUNT], [F_DEFAULTDAYS], [F_COUNT_M_POSTS], [F_MODERATION], [F_SUBSCRIPTION], [F_ORDER], [F_L_ARCHIVE], [F_ARCHIVE_SCHED], [F_L_DELETE], [F_DELETE_SCHED], [F_POLLS] FROM [backup_db].[dbo].[FORUM_FORUM]
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_FORUM] OFF
go
-- FORUM_CATEGORY
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_CATEGORY] ON
INSERT INTO [destination_db].[dbo].[FORUM_CATEGORY]([CAT_ID], [CAT_STATUS], [CAT_NAME], [CAT_MODERATION], [CAT_SUBSCRIPTION], [CAT_ORDER])
SELECT [CAT_ID], [CAT_STATUS], [CAT_NAME], [CAT_MODERATION], [CAT_SUBSCRIPTION], [CAT_ORDER] FROM [backup_db].[dbo].[FORUM_CATEGORY]
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_CATEGORY] OFF
go
-- FORUM_TOPICS
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_TOPICS] ON
INSERT INTO [destination_db].[dbo].[FORUM_TOPICS]([CAT_ID], [FORUM_ID], [TOPIC_ID], [T_STATUS], [T_MAIL], [T_SUBJECT], [T_MESSAGE], [T_AUTHOR], [T_REPLIES], [T_UREPLIES], [T_VIEW_COUNT], [T_LAST_POST], [T_DATE], [T_LAST_POSTER], [T_IP], [T_LAST_POST_AUTHOR], [T_LAST_POST_REPLY_ID], [T_ARCHIVE_FLAG], [T_LAST_EDIT], [T_LAST_EDITBY], [T_STICKY], [T_SIG], [T_MSGICON], [T_ISPOLL], [T_POLLSTATUS])
SELECT [CAT_ID], [FORUM_ID], [TOPIC_ID], [T_STATUS], [T_MAIL], [T_SUBJECT], [T_MESSAGE], [T_AUTHOR], [T_REPLIES], [T_UREPLIES], [T_VIEW_COUNT], [T_LAST_POST], [T_DATE], [T_LAST_POSTER], [T_IP], [T_LAST_POST_AUTHOR], [T_LAST_POST_REPLY_ID], [T_ARCHIVE_FLAG], [T_LAST_EDIT], [T_LAST_EDITBY], [T_STICKY], [T_SIG], [T_MSGICON], [T_ISPOLL], [T_POLLSTATUS] FROM [backup_db].[dbo].[FORUM_TOPICS]
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_TOPICS] OFF
go
-- FORUM_REPLY
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_REPLY] ON
INSERT INTO [destination_db].[dbo].[FORUM_REPLY]([CAT_ID], [FORUM_ID], [TOPIC_ID], [REPLY_ID], [R_MAIL], [R_AUTHOR], [R_MESSAGE], [R_DATE], [R_IP], [R_STATUS], [R_LAST_EDIT], [R_LAST_EDITBY], [R_SIG], [R_MSGICON])
SELECT [CAT_ID], [FORUM_ID], [TOPIC_ID], [REPLY_ID], [R_MAIL], [R_AUTHOR], [R_MESSAGE], [R_DATE], [R_IP], [R_STATUS], [R_LAST_EDIT], [R_LAST_EDITBY], [R_SIG], [R_MSGICON] FROM [backup_db].[dbo].[FORUM_REPLY]
SET IDENTITY_INSERT [destination_db].[dbo].[FORUM_REPLY] OFF
go
I know I will need it again.