Try to set aside special time with each of you where she gets your undivided attention, bubs will take up a lot of your time and attention so this will help her avoid feeling like she's been replaced and becoming resentful of the baby. Including her as a helper will be super helpful too. Baby doll idea is great! We are also getting a special present for our toddler from the baby, not sure what yet
I just had my second baby 6 weeks ago, 16 months apart, don’t be afraid for your first to hold the baby (obviously with help from an adult) say things like “that’s your baby brother” etc, you could say things like “we have to be gentle with baby brother (or his name)” try not to raise your voice if they go for their face while learning to be gentle as it can be discouraging and make them not want to be near the baby or anything to do with him, I’ve been doing this with my first and he’s going really good and has started rubbing the baby’s head and giving him cuddles, although we’re still working on him not taking his baby brothers dummy out thinking it’s his 😅
Mine are 16 months apart so I know your concerns. Get your girl a little dolly so she can feel like she’s also looking after a baby. Really helped my boy. Also when your little girl meets your son, try to have your son in the bassinet and not holding him. I didn’t hold my little girl when he first met her. All the best xx