[ODE] How can I make a chair not to use dJointCreateFixed() ?

[Roel van Dijk]

You usually create a body and a geom and then add that geom to the body. But 
you connect multiple geoms to a body. To achieve that you can use the 
Geometry Transform class:
http://opende.sourceforge.net/ode-latest-userguide.html#ref87

You add your geoms the geometry transforms and then add those transforms to 
the body.