[edelweiss]

You should probably try asking on a BJD related site like Den of Angels or Angels Unlimited. It is rather unlikely you will find your answer on this site, not really an active group of BJD people here.

I happen to know quite a bit about BJDs, I'm a collector myself. The only dress form I have seen is the one from Volks, but I am not a seamstress so I don't really go looking for that kind of item.

What size are you sewing for? I know you said 1/3 but are we talking 58cm, 60cm, 65cm? Taller? Boys or girls? Which doll body types are you aiming for as your market? If I come across something it would be better to know what doll type you are looking to fit the clothing to.