Yes, I know, It sounds self righteous. There are just some tricks that I have figured out on my own or been taught by my mother that work. And I mean, ALWAYS WORK.
My kids' doctor has been expecting the arrival of his twin grandbabies. At my son's appointment, the doctor announced that they had arrived and that his daughter was having an especially hard time with her 20-month old being jealous of the twins. I told him that my mom taught me to get the last "baby" involved with the new baby and they won't be jealous. It also inducts them into Big Kidhood.
I told the doc that from the time my second was born until our latest, I have always put the youngest in charge of getting a diaper and a wipe for the baby. Then, as I get the bottom ready, the young one holds the wipe in their hands and is the "Wipey Warmer". Essentially you need the cold wipe warmed so as not to alarm the unsuspecting baby. Who better than the now-big-sister/brother? It works like a charm. The diaper change only lasts a minute and then they are tired of helping and ready to go back to their toys. But it's just enough time to make them feel special and helpful. Isn't that what we all want?
And if you do it right, they will (as BBG puts it) "Be yo gawbage gurl" and happily take the messy diaper to the garbage for you. And they'll thank you for giving them the chance to be included.