[CentOS] Mock and Mock again

Question: If I use mock to build package rpmA from tarballA but rpmA has a dependency that can only be satisfied by package rpmB which must also be built from tarballB then how does the rpmB built from the tarballB get pulled into mock when building rpmA?

I am trying to build httpd-2.4.7 from Apache and that needs apr-devel and apr-util-devel > 1.4. I can build apr and apr-utils in mock but I cannot find clear instructions on how to get the custom built rpms into the mock build for httpd. I presume that the procedure it is so simple that nobody thinks it necessary to write it out but I cannot figure it out on my own.

Do I just build the things in order and leave them in the mock root for the subsequent httpd build to find?