for ($i=0; $i<`#of children to do`; $i++;) {
  $pid[$i]= open($created_file_handle, "$custom_call_statement -|");
  if ($pid[$i]) { waitpid($pid[$i], 0); }  # parent waits for child to
+ finish
      } else { 
        while (<$created_file_handle>) { $out[$i] .= $_; } # add outpu
+t to the array
    exit; 
  }
}
[download]

To be honest... I really don't understand your code above. Sorry...
But then... Here is a complete program that might help you. It forks 2 children and collects the children's output in an array.
Be aware that there is no error handling (can't fork etc.) yet.

use warnings;
use strict;

my $children= 2; # How many to fork
my @out;
my $first_child;

$|=1; # unbuffered output to see the effect

my $pid= open($first_child, '-|');
if ($pid) {
    # parent: Collects all output
    @out= <$first_child>;
}
else {
    # child forks again and produces output
    my(@child, @childpid);
    for (my $i=0; $i<$children; ++$i) {
        $childpid[$i]= open($child[$i], '|-');
        if ($childpid[$i]) {
            # parent
            # does nothing yet
        }
        else {
            # child produces some output
            my $j=10;
            while ($j--) {
                print "I'm child $i and will tell this $j more time(s)
+\n";
                sleep 1;
            }
            exit;
        }
    }
    foreach (@child) {
        # closing all child handles
        close $_;
    }
    exit;
}

print @out;
[download]

Actually, I've found a solution that works.
I'll post it here later in the day, when I have some time to copy it from the other machine(no, they are not connected in any way).

But thank you for the look.
And for my next trick, I'm going to turn it into a duck, or something that uses shared memeory, whichever makes me laugh more.