I found the button "Copy to other adapter" in the Multiplexes list. Still, that suggests that all 464 Muxes have to get copied and maintained to my 3 other adapters.
What i would really expect is a database where the muxes and transports are kept in one table, ordered by position. The adapters and diseqc info in another table, referencing the positions in the mux/transport table(s).