I can't thank Mario and Noel enough. Your advice has let me get on really well. I changed the drivers in BIAB to MME as Mario said and now can easily drop the tracks to midi or wav according to the track type.

When I had the tracks in Ableton at the same tempo as the original I was able to set warp on the tracks and that allowed me a reasonable range of tempos for the project.

One thing I did find odd though is this. When I rendered to WAV/MIDI from RealBand I didn't get an option for the destination folder, the rendering was saved in a sub folder of the original BIAB song which was used as a source for RealBand.

I thought that since these were stand-alone audio and midi that I could move the folder to another location. After moving the folder I found that the only tracks that would move to Ableton were the Midi and the RealDrums WAV. All the remaining RealTracks would not transfer to Ableton. I thought that perhaps I had exited RealBand before rendering was complete, so I tried again and confirmed that it was saved but I got the same result after I moved the folder. I tried playing the tracks individually using VLC. The RealDrum file did play but the RealTracks indicated an error saying that it could not find the file path. I moved the folder back to where it was generated and, what do you know, the RealTracks played properly and I could move them to my Ableton projevct. I can't really understand how it remembers the original location?
It's not fantastically important but it is a puzzle.

Kindest Regards

John