Mattel made the Barbie Li'l Friends that originally came from Rosebud in USA and later the Heart Family Twins. These were just little boys and girls that Barbie was baby sitting. Some boxes mentioned Barbie being "aunt" to them... These babies had a real baby look to them, a "tad" too big for Barbie though...

Later came Kelly that were supposed to be younger than the chubby legged bigger baby dolls, with a whole new body mold and straight legs that made her able to stand herself.

Other doll makers have had their baby dolls too, very similar to Mattel's "cuddly" baby dolls, but some smaller and some bigger. And then, when Kelly came to stay there were made copies of her too, bigger than our little darling, but with similar looks in the body.

Even Kelly have had a change in her body mold, and I'm not talking levers or other gimmicks here, but her leg joint. The Pony Riding Kelly/Shelly has another joint than the regular Kelly and Li'l Friends. Those sit with their legs straight in front of them, while the Pony Riding girl sits with hers wider, like on a horseback. A lot more realistic look to it. Put them in a sandbox and you'll see who of them sits like kids really do!!
There has been a few changes or additions over the years, to the body molds for Kelly doll and the biggest is yet to come in 2004....!

Some of the dolls are borrowed from my kid's dollbox - therefore the condition of hair and so...

Five of the different body molds used for Kelly dolls and her friends. Left to right:
1. Flailing arms of the Shopping Fun Kelly AA (her left hand is also pointing flat with a magnet but it is hard to see in the photo).
2. Regular straight leg body without any gimmicks (AA Picnic Kelly).
3. Sitting or spread leg body. With this joint Kelly (Keeya here) can sit without falling.
4. Bendy leg body. Marisa here can do a split or sit with her knees bent.
5. Swimming body. Tommy is the only doll made with the kicking leg feature and bent ankles.
There are variations to these features and a Halloween Party doll (Spider Kelly) has both bendy legs and flailing arms - with the original spread finger hands vs the one to the far left here.
 

New arms that swings to all sides and bigger feet on longer legs with a shorter torso, but still on a totally longer body is one of the new Kelly doll body molds from 2006-07. The "new" 2006 body to the left and "old" 1994 Kelly. Sea Pixie fairy compared to Pajama Fun (panda) Kelly.

Comparison with some Kelly sized klones.
Susy Sister, Mandy, Camping Fun Kelly, World Kid Japanese girl, Caitlin, Paula.

All the dolls but Paula has very similar body molds. Caitlin has another bend to her arms and Paula is totally different. Height of the dolls are the same.