>Is this possible? My experience so far has been that my VFP Interop assemblies have to be re-added to the C# project and then the service has to be rebuilt to get the new VFP code.

.NET Interop assemblies bind against a type library and create code from it. So if you make a change to the public interfaces of the COM object that code will break. It may still run until you hit a discreprancy, but it will run.

You can however make changes to the code only and that should work. VFP doesn't re-write ClassIds unless you tell it to so that should still work.

However, I would argue it's good practice to ship the VFP DLL(s) and COM Interop assembly as a package. if you're updating anyway - update all of them. The interop assembly should be separate anyway. This may still break code though if the public interface changes...