Well, less of a fail at least.
As I mentioned I've been looking for bettee articulated bodies for Hadley and Isla from 12 Dancing Princesses for som time. They're not only short (25cm/10") but also have those slim neckposts, so I thought it might be hard to find a match. So far I've been considering EAH Ashlynn Ella (seems to match skin tone but neck knob requires modification), Fairytale High (slim neck but tall, weird bodies, skintone might not match) and Disney Fairies Pixie Party by Jakks (slim neck, skin tone unsure, one blog review found the articulation lacking).
Anyway, since Roxanne of Roxanne's Dolls mentioned she had her Hadley and Isla on Liv bodies, I decided to try using the Super Model bodies I had at hand. Since they have about the same neck circumference as Liv and Barbie I had ruled them out, but...
Also, I think OHC Briana Joy might look better on Bel's body.
A bunch of comparison pics under the cut!
L: Isla(?) on Sarah's body, R: Hadley(?) on Juls' body, original body in the middle.
I think this might work!
I used different bodies since those were the ones I had at hand. Sarah is slightly darker and Juls slightly lighter than the original body (which doesn't match the heads perfectly either), so it's a matter of taste really. I don't have the AA Hadley and Isla so I'm not sure whether Bel would match them, but Liv Alexis' skin tone seems closer.
She can turn and tilt her head even if it's a bit tight. The neck looks a bit odd when she looks down, but not too bad. The vinyl does get a bit stretched over the bigger neck post, and I'm not sure how that will work out over time. I really really hope it won't split.
The Super Model body isn't quite as elegant as the original, but it's pretty close in proportions. As long as the neck hole doesn't split or anything this will probably be their bodies for now.
Since I was playing musical heads already, I did what I should have tried before ordering a Sarah and put OHC Briana's head on Bel's body instead. It's still not perfect - her head still looks a bit green in comparison and she's still too tall - but a better match overall. Poor DeeDee will have to be a floating head for a while until I can find an articulated Bratz or another Bel (although now that I've got one each of the super model girls I'd like to concentrate on other types of dolls for a bit).
Palm Beach Juls lost her body too, of course, but to be honest I never really bonded with her.
Same as above in different light.
All four Super Model skin tones, just for reference. L-R: Miri (with original head), Juls, Sarah, Bel
...and again in different light