Include her with helping, and definitely make it that little one is so excited to meet her and got her a present and I made it special that older one had to buy first teddy and he found it so important finding perfect one etc was amazing xx
I second what Chloe has advised. At the nursery I work at, we support the transition by reading them a book about becoming a sibling and advise parents to try and get them involved as much as they can, I.e. asking to pass/hold the nappy and wipes. If possible, see if you can find an hour or two where it’s just you and her quality. Lots of praise and words of affirmation will help as well.
We got a personalised book that was “you’re going to be my big sister” and got some gifts from the baby for the day they met each other. We also asked my little girl for help, such as passing a nappy or dummies etc!❤️