I've upgraded to the Ph2 rear lights on my Ph1 Megane some time ago. With the Megane, Renault unfortunately changed the wiring with the Ph2 rear lights:
The Ph1 model has a 3-pin and a 4-pin connector.
The Ph2 model has a 2-pin and a 5-pin connector.
Although the new lights have exactly the same shape and will fit the car, you cannot directly connect them, without having to do some modification to the wiring. I do not know about the wiring of the headlights, possibly this has been changed as well.
I presume that they've done the same with the Scenic Ph2 rear lights. I do like the Ph2 Scenic rear lights a lot more than the Ph1 model. When I trade my Megane for a Scenic somewhere in the near future, I'me sure that I will change the lights again if it is the Ph1 model.
There are different routes in upgrading to the new lights, with different costs. See the following topic:
https://www.meganeownersclub.co.uk/forum ... php?t=2439