Uncle Double D and the Lumpettes. Double D is more of a mother to the girls than the Kankers ever could be. He's secretly (or not so secretly) always wanted children of his own, but he and Eddy could never reach an agreement on adoption (how old, boy or girl, whether or not to adopt at all...) so he raises Mavis, Agnes and Hortense as if they were his own.
In terms of being completely insane.
He reads up on all the latest new-age parenting and child psychology books and is subscribed to children's highlights. He disinfects absolutely everything the girls might touch, afraid of germs and disease. He has the closest bond with Mavis, given her fondness for reading. But he helps all of the girls with their homework and asks how their day was while providing them with healthy alternatives to after-school snacks, to stimulate proper brain growth in growing girls. He's...a bit smothering. But well meaning. He coddles and dotes on Hortense the most, fearing for her safety given her accident prone nature. A first-aid kit is never far out of reach.
Agnes is the one he has the most trouble forming a bond with, be cause she takes after his partner in terms of being a stubborn mule. And she pulls away from his doting nature, and this breaks his heart because all he wants is to be close to her. But they do have their moments, particularly when Agnes needs and actually seeks out comfort.
Their relationship gets better and better overtime. Particularly after a slumber party she attended with her sisters when she was 12 stirs up some scary new feelings about boobs. And when Uncle Eddy and Big Papa Ed were nowhere to be found, Uncle Double D was there.