[Sanjip Shah]

@salveta Now you will have unhook the parent function from the action hooks and hook you customized function from child theme. http://themeshaper.com/2009/05/25/action-hooks-wordpress-child-themes/. And if the functions are pluggable you can just overwrite them with same function name. http://codex.wordpress.org/Pluggable_Functions. If you are not a developer you might have to take the help of of developer as it be too difficult for you to figure it out.