my %combinations = ( 
          co1 => [
                  [ qw(one two three four five) ],
                  [ qw(one one two three five) ]
                 ], 
          co2 => [
                  [ qw(one two three five seven) ],
                  [ qw(one one two three five) ]
                 ],
          co3 => [
                  [ qw(one two three five seven) ],
                  [ qw(one two three four five) ]
                 ],
          co4 => [
                  [ qw(one two three five seven) ],
                  [ qw(one two three four five) ],
                  [ qw(one one two three five) ]
                 ],
          );

reorg($_,\%combinations) 
  foreach(keys %combinations);

sub reorg{
  my($k,$h) = @_;
  foreach my $combiset(@{$h->{$k}}){
    my @uniquesets = 
       grep $_ =~ /\Aus/ keys %combinations;
    my $num = scalar(@us);
    
    foreach my $set ( @$combiset ){ 
       
      $combinations{'us'.++$num } = $set
      unless grep @$set  {<~~>} @$_,
              @combinations{@us}; 

    # where {<~~>} is 'these arrays match'
      # or the front N indices do or ...
    }

}