Chelsey is 5,5 months and we gave her a little sister 2 weeks ago, the first week she hated it and acted like a real brat, it made me feel very sad and thought she would never adapt, in the short time we have Chelsey she is very very spoiled by everyone, now i can glady tell u that she adores her little sister, they cuddle up and sleep together so dont get discouraged in the beginning, they sort themselves out just give them time
Include ur 8 year old in EVERYTHING u do with the baby or buy for her
Good luck!