Absolutely love it. But then I like Bibi and Coco. I would prefer Didi spelt like this though. Deedee looks a bit laboured or long-drawn out.
Didi would be a reaally hard name to match a sister name with. What is your older daughter called can I ask??
Polly, Lois, Greta, Thea, Nancy, Leila, Sasha, Esme....... those are names I can see with Didi. But it's not one that goes with everything, so excuse my curiosity about your first dc's name.
GL