Curate, connect, and discover
Everyone who's blaming Bianca should really be blaming Hades.
The man never even took his children down to the Underworld despite the fact that Maria would literally be there, she'd WANT to see her children, despite the fact that they'd be safe there with people to look after them. Zeus already knew of their existence, right? So what would Hades have said to him if Maria had agreed to come down to the underworld? And why didn't he use that excuse for Nico and Bianca?