In the stock rider system of NWN there's the ability to dual ride. I think that this could be a nice RP tool to have on the current riding system. It would also be convenient for those who do not have horses and need a ride fast to a gathering point (which would be in a rp reason too), having 2 choice of riding style, Normal, which would put the second rider behind of the animal handler, and intimate, which would put the second rider in front of the animal handler.