My current installation is 3lingual with url like: http://www.example.com/category/postname/ for the english posts and
http://www.example.com/category/postname/?lang=fr or ?lang=es for the french or spanish posts.
I have installed a multisite with 3 sites /fr/, /en/, /es/ and migrated all the previous posts to this new installation with urls like
http://www.example.com/fr/postname or http://www.example.com/en/postname (without the category).
I was looking to redirect all the posts to the new installation thru .htaccess but I am not sure this is possible because the previous english posts do not use the ?lang parameter.
Or should I use a redirection plugin ?