Include Parent functions.php in Child Theme functions.php

As per @toscho’s comments, the parent theme is always loaded after the child theme’s. In this way, if you want to override a parent theme’s function you can rewrite it and the original will be ignored, whereas any functions you didn’t rewrite are loaded and available.

There is no need to do it the other way around. If you are just loading additional files and defining actions and filters (as you should) there is no reason to worry about the order in which both function files are loaded, because at this point WP is just making an inventory of code to execute, not actually executing.

So, that gives you plenty of freedom to define additional settings in your child theme’s functions.php, even if the parent’s one has not been loaded yet.