It's not like Friedlind didn't have her own pleasant encounters with Uncle Wolf..
I've read Jonathan Carr's 'The Wagner Clan' so I'm well aware of the incidents you're referring to. Winifred was cowardly and concerned first and foremost about the 'family business' (and her own safety). BTW Winifred's other daughter Verena Wagner (on the right in the photo) is still alive.