Overall we never had issues and that surprised us. We thought DS2 was gonna a little bugger about the baby as he has really enjoyed being the baby and knew he wasnt gonna relinquish that postition easily. The boys had been sleeping with me and DH in the their room, so we re-did their room, got them big boy beds and nice sheets. Bought them each a present that we stashed away to be from the baby (the presents go along way to helping the sibling "like" the baby) We included the boys in all the scans, and they helped to choose something nice for the baby to wear. Each night they wanted to give my tummy a kiss good night and talk alittle bit to the baby.
They have both had afew adjustment issues as is normal- sometimes they have to wait for mummy to finish something with the baby but we also make a point of telling the baby - wait Im just with your brother, be there in a min- so it feels fair to them. They are very protective of her when we go out and dont let people touch her and if she is asleep they will push people away
They help us with nappy changes, making bottles, getting dummys all that kind of stuff.
We thought about what we would like, what would help us to feel comfortable and try to do that for them
Good luck