Yamaha styles can be converted to MIDI files according to this:

http://www.jososoft.dk/yamaha/articles/style2_1.htm

You would then import the MIDI file into BiaB or RB. As with all conversions if may or may not sound identical to the original style.

Maybe this would help with the Korg styles:

https://www.korg.com/us/support/download/software/0/312/2455/

Note that these conversions will not make a BiaB style; it will produce a MIDI file that can be loaded into BiaB. You might be able to create a BiaB style out of them if you want to put the time into doing that.

Also note that I have no experience in this field. The above is just information I got of the Internet.

On a side note Norton Music does sell BiaB styles that have be converted from Korg styles:

http://www.nortonmusic.com/contents.html

Whenever I get something stuck in the back of my throat, I dislodge it by drinking a beer.
It's called the Heineken Maneuver.

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware