Thanks for the reply Don.
I think I might have a go at tackling the delete user completely bit first!. Maybe if I study the data model around users and find all tables where user_id appears I might be able to safely remove them
Once I have done that maybe it will be possible to simply allocate one user_id as the desired master user_id and re-write references to the other ids on all other tables
Any pointers much appreciated
Regards
Richard