Safest way; export the track to an audio track, many ways to do it. Simplest, but most foolproof way, is to mute the rest of the tracks and merge it to a single audio track.

Then after you open the project in RB just use Adio - Import Audio, and import the previously saved track at the very beginning of the seq file (using a new blank track of course).

However, as mentioned in a different thread, you might want to try Realbnad; you likely have it already if you have BiaB. It comes free with recent versions.
It looks/acts much like Powertracks, but incorporates some BiaB features that PT does not.

I do not work here, but the benefits are still awesome
Make your sound your own!