Consider situation, when you create $mom1, $mom2, $son1 and $son2 in your main package. That sons cannot know anything about their parent objects without explicit setting this relation. According to OO conception, they inherit from classes, not from objects (instantiated classes).

My opinion is that it is not possible in your example, but you require something not compliant with OO.

I see only this way:

sub parent {
my($self, $parent) = @_;
$$self{parent} = $parent if defined $parent;
return $$self{parent}
}

[download]
Update: Or, to allow unsetting of parent: 
sub parent {
my($self, $parent) = @_;
$$self{parent} = $parent if 1 < @_;
return $$self{parent}
}

[download]

In reply to Re^3: SUPER in OOPerl is dumped with $self by pajout
in thread SUPER in OOPerl is dumped with $self by atemon

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