Hello Kelly! Welcome to the Disney Parks Moms Panel.
The largest group that I was ever in charge of organizing
Advanced Dining Reservations for during a Walt Disney World Resort Dining location was for 12 Guests. The challenge you will find in booking a table for 19 Guests is availability.
When making Advanced Dining Reservations, it is not required to link everyone together through a
My Disney Experience Account. As long as the Guest that books the Advanced Dining Reservations is there when upon arrival, all of the Guests will be seated at that time.
The easiest way to link Advanced Dining Reservations on My Disney Experience is to
have other parties link to your booking using the Confirmation Number and the last name provided at the time of booking. Alternatively, you can link Guests to your My Family & Friends list through your My Disney Experience Account and
Update the Guests on the Reservation from your own Account.
You are able to use the the My Disney Experience Mobile App and online site to look for and book Advanced Dining Reservations for you 19 Guests. The maximum number of bookable Guests for the Mobile App is 20 and up to 50 on the Dining location site online.
Good Luck!
~Todd