Several contributors to unity configuration in app.config ?

Question

Hi,

  I have an application with several layers. Each application contribute some <typeAlias> and some <type> to the <unity> node in app.config.

  I want to split the big app.config file and have one (or several) for each layer because :
-This file is getting too huge and is getting hard to maintain
-Having mapping defined for other interfaces of layers impli that I must have the implementation assembly of those layers, which is bad for reuse and unit testing.

  How can I merge all the isolated app.config files defining mappings for each layer so my final app can Resolve<>() every mapping in the end ? Is there a better way than running a custom tool that would do the merge at build time ?

Regards,
John.