Do i need to bring along the passport to prove that my grandchild is below 3 and I'm is 66 when entering Disneyland

Generally, they won't check the proof of ages when buying the ticket, but when getting into the park, the staff may ask you to show that if they doubt your age, especially for the preferential tickets. Therefore, it is best to take along your passports.

Comparatively, Dec. 14 may be more crowded, which happens to be during weekend.

You are allowed to take the milk powder and thermos into the park. Oh, and you can certainly take the scroller in as well. Don't worry!