I don’t fully get what you trying to achieve, but the from my point of view dynamic layers (BBFILES_DYNAMIC) are mainly used for bbappends only.
They prevent bitbake from parsing a bbappend in case the layer with the original bb file is absent.
I was trying to follow the example of the meta-freescale layer which has both .bb and .bbappend files within dynamic layers.
Having thought about it some more I realise that it could just be in one of the regular recipe-xxxxx directories and didn’t need to be in a dynamic layer after all.
