[arch-general] best practices for rebuilding packages

Hello. If I have a package build from aur that depends on a library, and the library is updated, and package from aur requires rebuild, is it possible to somehow track and automate that? In other cases maintaining such configurations may be the trouble as you have to remember what aur packages depend on your library. Another question: what about modifying aur/abs pkgbuilds, like I replace the whole configure line because I want to do so, but to do such a configuration for a new version of the package, I have to manually modify any new pkgbuild I get to get the same result. How to make it nicer?