my @seq= GetSequences(); # ( \@seq0, \@seq1, \@seq2, ... );
my @out= DiffMerge( 1, @seq );

sub DiffMerge
{
    my( $finish, @seq )= @_;
    my @diff= map {
        DiffToMerge->new( $_, $seq[-1] )
    }   @seq[ 0 .. $#seq-1 ];
    my @out;
    for my $i (  0 .. $#{ $seq[-1] }  ) {
        my @row;
        my $same= 0;
        my %sublists;
        my @flush;
        for my $d (  0 .. $#diff  ) {
            for(  $diff[$d]->SubList()  ) {
                $sublists{$d}= $_   if  $_;
            }
            if(  $diff[$d]->Same($i)  ) {
                $same++;
                push @flush, $d   if  $sublists{$d};
                push @row, $diff[$d]->Shift();
            } else {
                push @row, undef;
            }
        }
        if(  @flush  ) {
            for my $row (  DiffMerge( 0, values %sublists )  ) {
                my @subrow;
                for my $d (  keys %sublist  ) {
                    $subrow[$d]= $diff[$d]->SublistOffset() + shift @$row;
                }
                push @out, \@subrow;
            }
            FlushSublist( \@out, $_, $diff[$_] )
                for  @flush;
        }
        if(  $same  ) {
            push @row, $i;
            push @out, \@row;
        } else {
            my @r;
            $r[@diff]= $i;
            push @out, \@r;
        }
    }
    if(  $finish  ) {
        FlushSublist( \@out, $_, $diff[$_] )
            for  0 .. $#diff;
    }
    return @out;
}