An object representing a child may or may not have objects representing its parents, but this has absolutely nothing to do with inheritance (multiple or otherwise) in the OO sense. As I said earlier, the different meanings of "parent" and "child" in the real-world context vs. the OO context appear to be confusing the issue here.

Consider the following object model:

Person --- Person::Child
       \-- Person::Adult
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Each Person::Child instance has an @parents property which holds one or more Person::Adult objects representing its parents (in the real-world sense), yet Person::Adult is not Person::Child's parent (in the OO sense).

This example also answers the question of how to modify pajout's code to allow the child object to have an arbitrary number of parent objects (change the parent property to an array):

sub parents {
  my $self = shift;
  push @{$self->{parents}}, @_ if @_;
  return @{$self->{parents}};
}
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...but this is completely unrelated to multiple inheritance, so I question whether it's likely to tell you what you're actually trying to get at.