You should be able to drag them to the upper left corner (Drop section) and use them.

Hover your mouse over the WAV section of the Drop section in the upper left corner of BiaB.
This should reveal a Tip popup.

Freezing the tracks prior may help preserve the work.
Or just 'Open' the file in RB ..


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