@ Joelc: If I understand this right, you suggest to use a kind of merger device that merges RS-232 information that comes from and/or goes to two different devices (e.g. the pc and the Crestron system?) Sounds like a good idea, I didn't realise that RS-232 merging devices existed. Which brand/type are you using?

@George Mills: Ok, thank you for your advice.

@MarcK: Yes, I have the Meridian supplied rack. So you are saying that the M rack actually performs as an RS-232 merger? That would be great.
However, the next problem to solve then is the panel that is supplied with the rack that covers the front connectors. Looks cool, but it is not quiete user friendly that one needs a screwdriver to open it...