foreach my $who (@list) { 
    #my $sub = "\$ln =~ s/scrooge (& donald)/$who \$1/g;";
    print "$who\n";
    foreach my $ln (@lines) {
        #eval $sub;
        #print "$ln\n";
        print $ln =~ s/scrooge (& donald)/$who $1/r, "\n";
    }
    print "\n";
}

##</code><code>##

$ perl -E 'my $x = "AAA"; $x =~ s/A/B/; say $x'
BAA

$ perl -E 'my $x = "AAA"; $x =~ s/A/B/ for 0 .. length($x) - 1; say $x'
BBB

$ perl -E 'my $x = "AAA"; $x =~ s/A/B/g; say $x'
BBB