How To Avoid Clean Build Using Mm-B On Android

I am building an Android Application that has a lot of C modules that has the sequence of Java->JNI->C code. I am currently building all the C modules using mm -B option in the Android baseport (Android source code) within the external folder. When I want to build all C modules, I call the individual modules' mm -B function one after the other. I have 2 questions in this regard.I wanted to know if there is a way to do incremental build on a set of modules. The scenario here is that I am building a set of modules one after another from a script. I have observed that all the modules mentioned in the script get built irrespective of whether a change has been made to it or not. This clean build takes time. Is there a way out of this?

Whenever mm -B is executed, the libraries built are placed in out/target/product//obj/lib/ path by default. I wanted to know if we can change this path and whenever the mm -B command is called, the libraries are copied to the corresponding modules paths and not to this common path.

I dont have much knowledge of the envsetup.sh that has the definition of these mm and mmm functions.