In my Win32 application I have the ability to run child processes with redirected input and output to anonymous pipes that I create and manage - this all works with the Crea
If you put a manifest on the child app, and if you use ShellExecute to launch, it will use the manifest and there will be a UAC prompt. (I prefer this to the "runas" approach in most cases.) This may allow you to launch the app the way you like without worrying about UAC, and get the elevating from the manifest.
However, you may have issues if the "manage" part you refer to involves a lower privilege app communicating to an elevated one. UAC forbids that.
It should be possible to set the environment variable __COMPAT_LAYER
to RunAsAdmin
before the CreateProcess call which tells windows to just force the run as admin via the compatibility flags. The environment variable can be deleted once the process is started.