Rails engine and routes

I have this root in my engine

devise_for :users, path_names: {sign_in: "login", signout: "logout"}, controllers: {omniauth_callbacks: "omniauth_callbacks", :invitations => 'invitations', :registrations => "registrations", confirmations: "confirmations"}

How can I make sure this route gets used by the rails app too ?
I am already using this in the rails app.

 mount Xmppify::Engine => "/"