There seem to be two distinct problems. The BV7 is not able to send a HD source (DVI) to the RF modulator for the link rooms.
The usual way around is to split the DVI output and to convert one of the signal to SD and send it through the Scart of the BV7, in addition to the DVI connection.
The other problem, is that even if I connect a SD source and name it PC, I cannot activate it on my MX7000.