First off, when you make them, make them on the figures OBJ mesh, so that you're sure they're in the right place. (Export the relevent body part or parts to obj, check ONLY for morph targets, open it in your modeling program.) Import your obj without centering, figure height, etc. checked. Parent them to the body part they most overlap -- necklaces to the chest, for example. Try checking "inherits bends of parent." For small props that don't have multiple parts, don't conform. (I think "conform" wants the prop to have joint parameters, falloff zones, etc.) Then save into prop library and check "smart prop." I've never had any trouble.