Merging a user does not merge bookmarks, private message, nor group membership

Hi there,

When deleting a user and merging to another user there seems to be a problem.  Private Messages sent by the deleted user are lost, so too are bookmarks, and group membership is lost. 

Example (color coding below just to help the eye follow along the different items expected to be moved):

User1:

• Joined group1 (public open membership)
• PM’ed a user called Admin
• Received a PM from a user called JaneDoe
• Bookmarked a thread calls ‘install problems’

User2:

• Joined group2 (public open membership)
• PM’ed a user called JohnDoe
• Received a PM from a user called Emma1986
• Bookmarked a thread calls ‘license issue’

Action:

• Delete User1 and reassign to User2.

Expectation:

1. User1 does not exist in the system and User2:
2. Joined to group1 (public open membership)
3. Joined to group2 (public open membership)
4. PM history shows a message to a user called Admin
5. PM history shows a message to a user called JohnDoe
6. PM history shows a message from a user called JaneDoe
7. PM history shows a message from a user called Emma1986
8. Bookmarks lists a thread calls ‘install problems’
9. Bookmarks lists a thread calls ‘license issue’

This is not happening.  All the bookmarks, PMs, and group joins from User1 (now deleted) are lost. 

I would expect when the system merges a user, it would move across more that the name against historical posts.  It's currently losing a lot of important information.