Hello Jayma!
Welcome to the Disney Parks Moms Panel!
I am so excited for you!
Be Our Guest Restaurant is one of my favorite dining venues at the Walt Disney World Resort.
I have recently had lunch there, and it was great and very convenient to pre-order online. This makes checking in at the restaurant so much faster, and I highly recommend that you do so. As for substitutions, you won’t be able to make them online. When you pre-order online, upon arriving at the restaurant you will be directed to cash registers to make the final payment for your meal. That’s when you will inform Cast Members that you will be using
Disney Dining Plan entitlements to pay for your meal, and that you would like to substitute your beverage for a dessert. Note that substitutions are not guaranteed, so always confirm with Cast Members.
Thanks for bringing your question to the Disney Parks Moms Panel, Jayma! I hope this helps you while planning! Please stop by real soon with more questions.
Best magical wishes,
Thiana