I had a setup that had a BM4500, sw 1.6 (1 way), a Beolink Video MKII (1615?), a TV-box (Auvisio)and a computer Monitor (Mermaid) in the link room. Main room is BS9000, BS5 and BV7-40 MKIII.
It was possible to control mainroom video-sources by TV, DTV, DVD....Picture and sound via RF modulator. BM4500 switched to A.AUX.
Mainroom audio-sources could be controlled by LINK-RADIO, LINK-CD..... BM4500 switched to A.AUX.
Local audio-sources controllable by RADIO, CD, A.TAPE...
BS4500 was not affected when the mainroom audio was controlled in the mainroom...
I did not test sound, because no speakers were connected to the BM4500. But I think you have to change the wiring on the datalink cable, because BL Video "expects" a video source being connected, and Beovisions have different audio inputs. Option setting for BM4500 was 2.6.
This did NOT work with 2-way audiomasters like BM7000, BC9500.
Hope this helps.
Stefan