C.L.
This is a very similar situation to what we had. I really wanted to deal with our similar sleep situation before the baby came, but looking back now (our 2nd is here and 3 months old) I wish I would've not stressed. First of all, as we neared our due date, my daughter woke more and more but I know now that it was just her stressing about what was coming and me changing. The older sibs seem to "know" more than we think they do. Secondly, the toddler will wake up with the baby at the beginning. I remember looking at her when the baby was just a couple of weeks old and seeing bags under her eyes and I felt like a terrible mom. However, I realized we were ALL sleep deprived and we were all doing our best with the big change. And sure enough, it didn't last long and now our once, light sleeper can sleep through anything and is getting better sleep now than she ever has. It may be a bit of adjustment for Sawyer, but you'll both manage. It really didn't take too long. Best of luck!