Welsh friend living in Brittany and struggling to learn French, responded to me accepting his Facebook 'friend request' with "well well well bienvenue". What is an appropriate French response?
« Bienvenu ! » is a pretty direct translation of "Welcome!" and gets the same direct response you would give in English, in which case you have several options -
« Merci ! »
« Merci beaucoup ! »
« Merci bien ! »