Scrooge McDuck is really the maternal grandfather of Paperetta Ye-ye, Glittering Goldie's granddaughter?

If he is we have no proof of it. Beacuase when she calls him 'grandpa' she does it in a rude joking way, and he quickly denies being her grandfather. I hope that helped. Personally I choose to believe she isn't and that they didn't have an affair, because sex doesn't exist in Disney as far as I'm concerned.