Out of curiosity, why? I don’t think UM has the same notion of a “managing server” (Broker Server) with independent messaging instance (Broker). In effect, the prior setup you had were 2 independent messaging instances. The IS instances connected to one or the other. Is there a constraint for spinning up a separate UM instance for test?
In dev you have active/passive? Hmm. I get using active/passive in test to mimic what is in prod. But for dev, seems excessive?
Did you have active/passive with Broker Server in dev?
In any case, I do not know how to get a single UM instance to support independent “message networks” the way Broker Server does with Broker. Perhaps someone else has an approach – would be interested to hear what it might be. Given that IS publishing and subscribing is all based upon document type, unless there is a way at the IS level to segregate published docs there may not be an approach with a single UM. Client prefix comes to mind but I don’t think that segregates things – just helps with publish order and subscriber “clustering”.
If your IS subscriptions have different names between Dev and Test, you can try the DurableNameFiltering option under DurableConfig in UM. It should allow you to designate each message to a particular subscriber. In order to enable it when you publish from IS there was something you need to set… subject name, or something similar.