Composing several bounded contexts in DDD

We're developing a comprehensive domain model encompassing 7(!) models/bounded contexts spanning several teams. We are yet to decide whether each one of the BCs is entirely disconnected from the others (being orchestrated by a layer above) or whether they are going to communicate via domain-events.

The application under development is for all purposes a SWT/Swing single-threaded application, so no fancy distributed mumbo jumbo between the different BCs is needed.

Yet, a big question remains: how to integrate all those different models? Should it be the Application Layer to undertake the task? If yes, and since in some (hopefully, few) cases the wiring and order ends up being complex, isn't the Application Layer the wrong place to do that?

For instance, consider the use of case of assembling a very complex synthetically created human (AssembleHumanoid). We have bounded contexts relating to the circulatory system, to the bone structure, the nervous system, ventilation system, coordination, immunological and mental systems and still the sensor system (lol, this was just all made up as you might imagine).

Wiring up all that stuff in the Application Layer feels kinda wrong. The obvious solution seems to be to create a 2nd Domain Layer just for orchestration matters. I've looked up but Vernon's Implementing Domain-Driven Design doesn't directly touch the issue (although he gets near @ p531, "Composing Multiple Bounded Contexts").

What are your thoughts on the matter?

I'm right now tackling the same questions as you. My role in my project is architect and we have identified 5 BC's. But we are one team and intend to develop theses BC's within one large application. So our BC's are modules within a larger insurance application where each BC speaks its own ubiquitous language (Treaty, Reinsurance, security, medical risk assessment, premium). But I have given this a lot of thoughts and I think we'll send updates to other BC through Domain Events. Our client is a MVC site that will consume our service layer. But My intention is that application layer have that kind of granularity so it will manage to perform the main task for the client without letting the client MVC project to coordination to other BC's.

We uses some shared Kernel between BC's but not for communicating. We do use DDD integration pattern where we have reference to other BC through Value Objects. We also have som BC to act like Factory, for example Security BC are creating different user roles for other BC's.

But when it comes to execution of a use case that actually need to to some final task in other BC's , Domain Event comes to rescue.