Remember that at some point of the child's lifetime, it was the parent. Just do something along the lines of:

#!/usr/bin/perl -w
use strict;

our $Parent_PID = $$;

# ... Many interesting lines of code ...

my $pid;

# The mini-loop below will re-attempt the fork()
# in case of errors, that are usually transient
# resource shortages. You might not want to do this
# in your scenario...

while (($pid = fork()) < 0) { sleep 5; }

if ($pid) {        # Father

  print "father: the child is $pid\n";

# ... Interesting code to wait for the children ...

}
else {             # Child

  print "child: My parent is $Parent_PID\n";
  print "child: I am $pid (or $$)\n";

}
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Hope this helps you.