Connecting to a service level add-on from another service?

[gidsg]

In the case where we have created an add-on at a service level, then subsequently had a need to connect to this from another service in the same app, is it possible to configure this (without re-creating the service at an environment level)?

An example would be:

We have Service A (Backend Service), which has a Service Add-On Aurora Postgres.

We have Service B, (Worker Service), which needs to connect to this Aurora Postgres instance

[gidsg]

This sounds like a duplicate of: #4275 (so closing)