Hey Howdy Hey Nicole and welcome to planDisney!
Lightning Lane Multi Pass is a great choice for a trip to Walt Disney World Resort to spend less time waiting in line for attractions and more time enjoying the parks. This will also come up big time for the ages of your kids! The lines for many attractions in the parks are engaging but still can get a little boring for the younger crowds. This access will hopefully make the wait time much less and a smoother theme park experience with less risk of meltdowns!
OK, so regarding the details with Lightning Lane and your kids, you are correct that Guests younger than age 3 do not need theme park tickets to get into the parks. They also would not need anything other than your access to Lightning Lanes. As long as you purchase for yourself, your 2 little ones are free to join you in the line and on the attractions. The biggest thing when making your selections is to be mindful of any height requirements. other than that, you should not have any issues.
Another helpful offering Disney has for Guests traveling with little ones is
Rider Switch. Say you and your 2-year-old want to experience an attraction but it's nap time for your 3-month-old. Just visit the Cast Members at the front of the attraction and ask about the rider switch. The Cast Members will be able to give you access to the attraction so you and your younger one can experience the ride while an adult is with your other child. Then you should be able to switch and the other adult ride with your 2-year-old. This can be a great way to let everyone that can have an opportunity to ride the attraction for the full family experience.
I hope you have a Magical time during your upcoming vacation. If you have any other questions please feel free to let us know, we are always happy to help!
To Infinity and Beyond,
Nick