The process class is used to make a process object when your geode is
started. It then runs in its own thread, the process thread. Your
GenApplication is in the UI thread (usually) and is not at all attached to
the process object. In fact, the process object can't be a child of anything
(it's not even a true object) since it has no instance data to link it into
the tree.
What you can do is use the GeodeHandle to get the application object optr
using GeodeGetAppObject. You can then talk to the application object using
that optr.
If you are trying to add children to an existing program that is not
designed to utilize those children, it would most likely die a horrible
death. Some programs expect child objects to be at particular positions among
the siblings. Also, it would be nearly impossible to get the program to use
the new children for anything.
Nathan