@falktx 2UIs for the same plugin instance, then you are fully right that LV2 already provides all you need.

My (and Jatins) ideas were "only" about the communication between two plugin (DSP) instances.

But it would be a "nice to have" if host makers can provide an optional feature to (i) clone a plugin instance with all its current parameters and to (ii) keep different instances of the same plugin (DSP) synchronized. 🙏