For me, I open the file in Realband, and then simply drag the tracks from there to Reaper.
Once I 'Save' in Reaper (due to Reaper prefs) I have a Reaper ready project on another drive.
And far as I can tell, the original BiaB/RB file is still untouched and in the original location.
So I keep it as long as needed.

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