OK... you will need to do what I suggested but if it still moves then there is something else that is throwing it off. When you positioned the imported OBJ into Poser was the figure in its zero position including zero BODY and hip? Was every scale and morph dial at zero? i.e did it exactly match its own geometry? You can check by importing the figure's OBJ with none of the import option boxes selected. They should line up exactly.

Would it be possible to post a screen shot? There may be other factors that should be looked at.