quick and dirty, maybe could been added as feature when user registers and has made comments before
‘UPDATE wp_database.wp_comments SET user_id=’User_ID_our_member_got_after_succesfull_registration’ WHERE comment_author_email=”his/her_old@used_before_mail.com”;’
Did this end well? Are we talking about Mystique version 3+ or the 2.something version?
With these instructions i get eg: domain.com/register full load of theme but empty page/post page or domain.com/index.php/register stripped CSS version but registration of BP appears
(checked nginx rules, also default BP theme works like a charm)