Lots of reading books about new baby, watching a Dora DVD "Big Sister", lots of talking about what was going to happen and how she was going to be "Mummy and Dadd's helper", No 2 buying her a baby of her own which he gave at the hospital - and lots more chat about the pending arrival. The important bit also came after the arrival - letting lots of interaction happen between them, lots of touching and playing, passing nappies and getting her to feed, change and put to sleep her baby at the same time as No 2 was getting all these! Making sure that No 2's needs were met, if not immediately, then as soon as the activity with No 1 ended. All these worked a treat for us, and No 1 was as happy as a larry when No 2 showed, and there has not been much trouble since (now in month 10!)