Object dependent positioning assistance

What I need to figure out is how to make one object's position and normal be affected by another object's. I would compare this to planetary orbit. I want to do this without mounting objects.

Oh and this would all be accomplished client-side.

I have tried using

MatrixF worldMat = decObject->getWorldTransform();
	worldMat.mulP(pos);
	worldMat.mulV(normal);

and the object just disappears.