16 month age gap, how do I make the transition smooth from 1 kid to 2? advice please!

Amanda
Does anyone have any advice for how to make the transition from 1 to 2 kids smooth? I want to make my daughter feel as included as possible in this life change, but I also know that since she'll only be 16 months, there isn't really much she can do to be the "helper."  Someone my mom works with was talking about how she has 2 kids with the same exact age gap (even her first is a girl and second is a boy like mine), and she said that her daughter was TERRIBLE while she was on maternity leave. I'm starting to get scared for what it will be like, and worried that I won't handle behaviors and balance everything effectively.  I love Amelia to pieces, but she is starting to enter that tantrum phase of childhood. What's it going to be like when there is a toddler and a newborn? 😬