Why not write something on their blackboards, inviting them to write on your's.

hello my friend! 你好我的朋友！ Bonjour mon amie! You might want to correct my Chinese :)

Some of people here have so many people in the "friend's" list that it's impossible to give one's attention to everyone.

best friends seriously in italki they are very different and many also ....... but busy busy .. Just ask them and they will respond thanks