How to transfer chat history that is backed up on Macbook for Line Messenger to new iPhone 6S ?

I had an iPhone 6 and recently bought a new iPhone 6S+. Before selling my iPhone 6 I backed up my iPhone 6 via my own computer by doing a sync with iTunes. I had Whatsapp,Wechat and Line Messenger. When I got the new iPhone I did a restore. Ally my applications and Chat messages came back accept for my Line Messenger chats. I can see them and find them on my computer but for some reason Line will now allow me to restore them on my iPhone. I get an error message telling me " The LINE account on your previous device will be deleted. Also, by logging in, your chat history will be deleted. Continue?" 😠 ***??

There has to be a way to recover the chat history if I can still see it on my Macbook. Need a genius to help me here.