The end result is undefined. There is no priority system or formal override logic.
You shouldn't have that kind of "override feed"...
The basic alternatives are:
- Patch each package in its own feed. Replace the normal packages with your versions.
- Define new package with slightly different name (e.g. "priv-packageX") and if some other packages depend on this, you can add a PROVIDES statement in the new Makefile where you say that this new priv-package provides package, so that the old one does not get automatically pulled in due to dependencies.
The easier option is likely patching the packages directly in respective feeds.
Ps.
There was years ago an override system but it proved to be problematic and was scrapped.