Filtering packages from unmanagedSources in SBT

Question

This should be very easy, but I am missing something. I apologize for the too-basic question.

I am reorganizing some code. I'd like to get the main package fixed, and then I'll have to modify code in some packages that depend upon the main package. Temporarily, I'd like for those dependent packages not to try to compile in my sbt ~compile world.

I know there exists a setting, excludeFilter in Compile in unmanagedSources, but I don't know what syntax I should use to keep whatever default exclusions are there but to add an new exclusions for (deeply nested) source directories that correspond to dependent packages.

Many thanks for any help!