PackageCompiler. Re-use of system image

Parallel to the StaticCompiler i am also trying out the PackageCompiler. A problem that i have with it is that with the standard call

using PackageCompiler
create_library("myPkg", "myPkgCompiled";
                      lib_name="libmypkg")

it refuses to run if the folder for the compiled library already exists. That means that i have to delete the folder or use --force. Then it will repeat the whole 5min process of assembling this folder every time I make a small change and recompile. Since i still need to figure out basic things with trial and error at the moment this is quite an issue.

So my question is: Is there a flag to tell the PackageCompiler to simply use the folder structure from last time and merely replace the object files for my actual code?