This option is not available as such for now. However, if you wish to make an intermediary stop that is not on the initial route of the ride, you can do so by changing the ride destination to the intermediary stop once your ride has started. You will receive a new price estimate that you will have to confirm. Once you have accepted it, your driver will see the update on his app and will have to accept it too. Once you have arrived at the intermediary stop, you can change again the destination to the final one. The new destination change will work as the previous one: you will be quoted a new price estimate that you will have to accept for it to be effective. Once the driver accepts this change, you can continue your ride until your final destination.