The SiS little sister dolls are definitely still around, saw them at TRU yesterday. There are also some versions that come with the big sisters, which also have way nicer sculpts and clothes than regular playline Barbies by the way.
Testing out my doll stuff:
Some sandal-type Barbie heels actually look the right size and fit on MMS 1st feet, but you'll have to put in a dab of postertack to keep them on. I also have one pair that is particularly small and thin with an ankle strap, fits nicely and stays on. There is a chunky wedge heel mold that also stays on okay and looks pretty good, it's on the "sassy" 100 poses doll right now. Everything else (sneakers, boots, standard heels) is too big.
Skipper shoes are a total no-go, Kelly ones are way too small but if you pull off the feet boots look okay. I have a pair of sneakers I mugged off a thrift store Olsen twin doll, they look like they might fit but I can't get my Dollfie's feet out of them to try. No on Liv shoes or Disney's HSM/Hanna Montana/whatever they're pushing at the time shoes. Fashion Polly shoes are too small, you can put on the boots if you take off feet if you really want though.
90's-era Kelly clothes fit okay but are crop-tops and miniskirts. Mystery Kelly knock-off clothes work surprisingly well. Modern holiday Kelly dress fits as a long shirt really nicely; new Kellys (Kellies?) are skinnier than old ones so their clothes look good, they only seem to sell them separately for holidays though! Juku Couture socks and elastic skirt fit.
Bratz pants are passable as baggy pants, most are slightly short on Bratz and the right length on Shinkis, but look bad at the waist as you'll have to tape it or add new velcro. But they look passable with a shirt on to cover it.
I also have a small Magical Melody DoReMi doll (weird thrift store find), those clothes fit but are short.
From my BJD clothes, a Fairyland Pukipuki dress fits as a babydoll top. The bloomers would fit if I hadn't broken the elastic.
Fashion Polly clothes will occasionally fit and look nice when they do, since they're plasticky and match Shinkis hair and such. Look for jackets that open in the front. You can get dresses on as tops and they would be great if the chests matched up. =#
Hats are really hard to guage since there's so much head size variation. Fashion Polly hats fit on most of my Shinkis, but they are the small-headed ones. Fashion Polly wigs are a nice fit on a bald Zelno!