If the BC2300 works now with your Beo4, you do not need to change its Option (probably #1). As you have read, you need to set up the Beoremote One to send IR commands.   There is no "pairing" of the remote to Beo4 Audio devices; pairing is a Bluetooth concept.  It just spits out the IR codes and whatever can see them reacts.  Thus your Beo4 will continue to work with the 2300.  (I *only* use my BR1BT in IR mode, so I don't know if it switches back and forth between IR and BT automatically for MUSIC vs. TV.  Hopefully someone else will advise.)

Thanks a lot, I will try to make the BR1 send signals to “Beo4 Audio” then, there is a section on that in the manual.