so we were a bit different. DD1 was present for the birth of DD2. At the time DD1 had turned two a month a bit beforehand. We never had any issues with her and DD2. We kept everything normal for her, we didnt make a huge fuss about anything either. After DD2 was born she and dh went out and got me a few things whilst we waited to be discharged (was home the same day as birth), and dd1 got her new sister a teddy bear penguin. On the way home we asked her if she would look after DD2 and make sure she was happy. But besides that we didnt nothing different. At home she was my helper, because thats what big sisters do, they help their little sisters and make sure they are happy.
When people came she had already told dd1 that people wanted to come and she her new little sister because they thought little sister must be special to have such a special big sister like dd1.

Mind you dd1's personality is very calm and relaxed. And I think that has played a huge part in how she responded to having a sister. Take your own child's personality into consideration and make sure you counteract that first before you make plans that may not work with your child.

This time round both girls know about sprout. DD1 is team sister, DD2 is team brother. They are very excited, and at the moment are really enjoying collecting things for sprout.
Other thing is I would be careful about how much fuss people make of the older siblings. Because that can backfire in the long run. I have a friend who had everyone make a huge fuss of big brother when little brother arrived. After the first couple of visits older brother expected the fuss from people, starting playing up and causing mischief because he got used to the added attention and gifts and what not.

Honestly, consider your own childs personality and how they respond to new situations. Communication is always good, and just make sure that you dont create an inbalance that lasts long term and could cause you more trouble in the end.

GL! xo