Well - that is the more perlish approach to adding elements to the array.
This works:

   push @{ $Dad->children }, new child_t(type=>"Flower Child");
[download]

This is closer to the syntax you were attempting (also works):

push @{ $Dad->children },  child_t::new('child_t','type',"Wild Child")
+;
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However, as others have pointed out, Class::Struct is a stepping stone into OO perl programming.
I abandoned it fairly soon after learning the many more powerful constructs in OO perl.

I'm still learning (after using perl for 8 years), and heading towards Moose (Which is sort of built-in to perl6).

Update: The second example above is unnatural - here is a better way:

push @{ $Dad->children },  child_t->new(type=>"Natural Child");
[download]