Each individual component only knows about its inputs. So and non useful answer to your question is that the 565 will only know about its D1 and not that of the 562v or 518.

Hopefully a more useful explanation is to look at it from the perspective of the sources available, ie those on the remote. In this case, each component knows how to deal with each source (or ignore it) and each component make up a little piece of the jogsaw that ultimately describes how a source is reouted from the initial input, ie D1 all the way through to output.

So for example you have a CD connected to D1 and DVD player on D2 of the 562v. The digital output of 562v's is connected to D1 on the 518 and the 518's output is connected to D1 on the 565.

When selecting CD, D1 on 562v is selected as input. For DVD, D2 is selected on 562v. However, for both sources, D1 is selected on both 518 and 565. For sources going direct into the 565, then the 518 and 562v will ignore the source and be selected as last valid.

So as long as there is a valid audio signal path from one compnent to another, all inputs on all components are technicallly valid for all sources. The limitation is the number of sources on the remote, some of which may be selected as phantom sources - same electrical connection but different presets.

Probably not easy to follow, but hope it helps.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).