Group projects to compilation units

[stephanos]

I have around 16 modules - I identified 4 groups (A, B, C, D) whereby D depends on C, C depends on B and B depends on A.

Now to speed up the build on my CI server I created 4 jobs that are triggered accordingly when a change was made to the source of A, B, C and/or D.

But how do I tell SBT to build, for example, all projects inside of B without building A but using the existing artifacts in the repository?

Cheers

Stephan