I've posted a couple of comments in other threads about converting Facebook login to Ubi login and after contacting support, it turns out it's pretty simple, no idea why the big secret and why this hasn't been mentioned in the topics from May or the recent unity conversation posts.
Delete the app from the your facebook profile and have the "notify" box ticked.
This will prompt a mail from BB with a link to create a password against your TSO profile so you then have a legacy account.
Link your profile to your ubi account (or create one)