What methods do you use to teach your toddler to give his/her baby sibling some quiet space to go to sleep?
I have a 2 1/2 year old daughter whose version of quiet is loud fidgeting. Her 9 month old brother finds it increasingly difficult to tune her out and go to sleep for a nap. I have tried occupying her in another room while I put him to sleep to no avail. She always comes trotting in to check on me sooner or later.
Napping together is something that has never worked out for our family. My daughter is a very active snuggler, and my son is Mr. Sensitive.
I don't have two, but have you tried running the dishwasher or other white noise to mask the sounds your DD might make? Put some soothing music on and have your DD dance around in the other room or color next to you, read books by herself, do some other quiet activity to music in the room witht you while you put the baby to sleep? Then tell her that as soon as the baby goes down, you will do something fun together (could even be folding laundry).
Even though I only have one, I keep relative noise level up enough and steady while she naps so that when I trip over something or shut a drawer, she doesn't hear it.
Your son might just get used to interruptions at some point, though. Our dog naps in the same room as DD, and a lot of times he'll bark loudly once or twice right next to her and she won't wake up. She heard him bark from within the womb, so it was never a big deal to her. Ironically, she does wake up if I'm in the room and shush the dog. Go figure.
Living happily and embracing adventures.