CreateInstance of COM object in specific process from C#

Context:
I'm writing a C# application (MyApp) which integrates with a .exe hosted COM server (ServerApp). I have no access to modify ServerApp in the short-term.

ServerApp can be started multiple times to allow multiple 'documents' to be opened, each in separate processes.

MyApp is initiated from a menu in ServerApp allowing two 'documents' to be virtually linked through MyApp, so I need to open a second instance of ServerApp (which I'm successfully doing with Process.Start()) and call some methods on ServerApp's COM API to navigate to a certain location in the newly opened 'document'.

The trouble is that Activator.CreateInstance(Type.GetTypeFromProgId("ServerApp.Editor")) always returns a ServerApp.Editor object in the ServerApp process which initially called MyApp.

What I'd love to be able to do is CreateInstance in the context of the new Process I started (the second ServerApp process).

Does anyone know how this might be acheived? I've been looking for something on Process (wondered whether remoting and CreateObjectRef might be the way forward)