#!/usr/bin/perl
use Data::Dumper;          # only for teaching purpose
$Data::Dumper::Indent = 1; # dito :-)

while(<DATA>) {
    chop;
    my($familyname,$memberstring) = split /\s--\s/,$_;
    my @members = split /, /,$memberstring;
    # tell each member that it's got a new family
    foreach my $member(@members) {
        push(@{$family{$member}},$familyname);
    } 
} 
print Dumper(\%family); # show the data structure in %family
# now output a list of members with their families
foreach my $member(sort keys %family) {
    print "$member can be found " . scalar(@{$family{$member}}) . ": "
        . join(" ", @{$family{$member}}) . "\n";
} 
__DATA__
FLINTSTONES -- BARNEY, FRED, WILMA
JETSONS -- MAX, TONY, WILMA
SIMPSONS -- LISA, BARNEY, WILMA, HOMER
ALCATRAZ -- ELIJAH, MAX, WILMA
[download]

$VAR1 = {
  'ELIJAH' => [
    'ALCATRAZ'
  ],
  'FRED' => [
    'FLINTSTONES'
  ],
  'HOMER' => [
    'SIMPSONS'
  ],
  'BARNEY' => [
    'FLINTSTONES',
    'SIMPSONS'
  ],
  'MAX' => [
    'JETSONS',
    'ALCATRAZ'
  ],
  'LISA' => [
    'SIMPSONS'
  ],
  'WILMA' => [
    'FLINTSTONES',
    'JETSONS',
    'SIMPSONS',
    'ALCATRAZ'
  ],
  'TONY' => [
    'JETSONS'
  ]
};
BARNEY can be found 2: FLINTSTONES SIMPSONS
ELIJAH can be found 1: ALCATRAZ
FRED can be found 1: FLINTSTONES
HOMER can be found 1: SIMPSONS
LISA can be found 1: SIMPSONS
MAX can be found 2: JETSONS ALCATRAZ
TONY can be found 1: JETSONS
WILMA can be found 4: FLINTSTONES JETSONS SIMPSONS ALCATRAZ
[download]

But before that - read the manual pages perldata, perlref and the one for Data::Dumper

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}