Hi, Diane!
Thank you so much for your question! You are correct, the baby would not be permitted on the course. Children must be at least five years of age to participate, and for safety reasons, strollers are not permitted to be used during race events.
While Disney does not offer childcare services that are available during race times, they do endorse the in-room childcare service provider,
Kid's Nite Out. With this service, a certified worker will come directly to your resort hotel room to watch baby while you and your sister are running. Kid's Nite Out is available 24 hours a day, 7 days a week, making it a great option for an early morning race event. For more information, just select the highlighted link above.
Please let me know if you should have any additional questions, Diane! I am here to help you plan as you prepare to take on The Dark Side.
Faith