package BasicX;

sub new {
...
}

sub someMethod1 {
...
}

sub someMethod2 {
...
}

1;

# ---------------------------

package BasicX::AAA1;

use BasicX; 

sub new {
  my $class = shift;
  my $args  = shift;

  my $newclass = BasicX->new(
                            {
                               DEBUG      => $args->{DEBUG},
                               SETTTING1  => $args->{SETTING1},
                            }
                         );

  return $newclass;
}

1;

# ---------------------------

package BasicX::BBB1;

use BasicX; 

sub new {
  my $class = shift;
  my $args  = shift;

  my $newclass = BasicX->new(
                            {
                               DEBUG      => $args->{DEBUG},
                               SETTTING1  => $args->{SETTING1},
                            }
                         );

  return $newclass;

}

1;

# -------------------------------

script.pl
----------
#!/usr/bin/perl

use BasicX::AAA1;
use BasicX::BBB1;

my $ObjAAA = BasicX::AAA1->new( { DEBUG => 1, SETTING1 => "this is it" } );
my $ObjBBB = BasicX::BBB1->new( { SETTING1 => "separate value" } );

$ObjAAA->someMethod();
...