Tracing syscalls of a process and all forked processes

I'm using ptrace to trace the syscalls of a process. After forking the process, I use PTRACE_TRACEME to start trace the the process. The code looks like this:

while (true) {
    int status;
    int gotPid;
    gotPid = waitpid(pid, &status, 0);

    if (WIFEXITED(status) || WIFSIGNALED(status)) {
        break;
    }

    if (WIFSTOPPED(status)) {
        handleTrace();
    }
}

Then there is the handleTrace function, which looks like this.

long syscall;
syscall = ptrace(PTRACE_PEEKUSER,
     pid, 8 * ORIG_RAX, NULL);

// do something with the syscall

// continue program
ptrace(PTRACE_SYSCALL, pid, NULL, NULL);

This is all good, but if the program forks (or creates a new thread) I also want to trace the child processes the traced process creates (and also the threads created by the process). I know that it can be done using PTRACE_O_TRACEFORK, PTRACE_O_TRACEVFORK and PTRACE_O_TRACECLONE, but from the man documentation, it is very hard to figure out how exactly it is done. I need some examples on this.

Edit:

I found a similar question here: How to ptrace a multi-threaded application? I tried it with the following code. This code tracks the system calls of the started process and it is supposed to track the forked processes too. It is run after a fork() in the parent process (the child calls a PTRACE_TRACEME and an exec()).

Edit2:

I made some more modifications on the code, with some more progress.

long orig_eax;
int status;
int numPrograms = 1;

while(1) {
    int pid;
    CHECK_ERROR_VALUE(pid = waitpid(-1, &status, __WALL));
    std::cout << pid << ": Got event." <