Here's a somewhat easier way:

#! perl -slw
use strict;
use Win32::Process::Info;;

my $pi = new Win32::Process::Info;;
my @info = $pi->GetProcInfo( $$ );

my $ppid = $info[0]{ ParentProcessId };
@info = $pi->GetProcInfo( $ppid );

print "Parent process name : ", $info[0]{ ExecutablePath };
print "Command line: ", $info[0]{ CommandLine };
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But as I explained earlier, it's not very useful for the OPs stated requirement as it always gives the same information:

c:\test>type junk.bat
dad

c:\test>junk.bat

c:\test>dad
Parent process name : C:\Windows\System32\cmd.exe
Command line: "C:\Windows\System32\cmd.exe"
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