Voldemort hated his muggle heritage and he didn't want to go by Riddle, so I don't think he would name his daughter after them. Lestrange seems more plausible but it's Bellatrix's married name and Delphi isn't Rodolphus's daughter. So that's why I put Black, I also put Rowle because she was raised by Euphemia Rowle. And Diggory because that's her fake last name. I'm starting to think it might be voldemort xD
