B-5 has to run in UVI Workstation. UVI is a shell similar to Kontakt. You can 'chain' other VI's inside UVI but they have to be designed to run inside UVI.

To chain unrelated VI's the way you want, B-5 to Melda Rotary, you need to use a Host app like Cantabile for Windows or MainStage for Mac. There is a free version of Cantabile available.

In a host you load UVI, select B-5 then direct the B-5 output to the input of Melda Rotary, and then output or the input of another effect.

In a host you can set up patches that enable you to change seamlessly from say B-5 inside UVI to another instrument running inside Kontakt/Komplete.

MainStage 3 | Axiom 61 2nd Gen | Pianoteq | B5 | XK3c | EV ZLX 12P
Hoping everyone stays safe and well and sees this through to the other side