Hi there, Stacy! Congratulations on your growing family!
You'll be glad to learn that your entire family can ride any
attraction that does not have a height requirement. On some attractions, such as The Many Adventures of Winnie the Pooh, "it's a small world," and Jungle Cruise, your family of four will be in the same ride vehicle, but possibly different rows, if applicable. While on other attractions like Dumbo the Flying Elephant and Astro Orbiter, you will ride in separate vehicles as they only accommodate two or three people. Also, if you will be wearing your newborn in a baby carrier, you may even be able to wear your newborn while you ride the attraction. Just ask a Cast Member at the beginning of the queue and he or she will inform you of any safety regulations.
You can also take advantage of
Rider Switch if a ride may not be appropriate for your newborn or if the baby happens to be napping and you don't want to risk waking him or her. This allows one parent to ride with your 2-year-old, and then when they are done, the other parent can ride and the 2-year-old can ride a second time.
Also, please keep in mind that there are
Baby Care Centers located in each of the four theme parks at Walt Disney World. These are excellent places to change your newborn, feed them, or even rock them to sleep. They also sell a few baby necessities like diapers and wipes as well as over-the-counter medication.
I hope this helps! Please stop by the Disney Parks Moms Panel again if you have any future questions.
-Linda M.