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Thank you for the tip about food. I have some concerns. Are there any ready to drink tetra pack milk available for kids in the US? Any particular brand to look for?
YES. PLAIN MILK, choclate milk and other flavors are available. Horizon Organic Low-Fat Chocolate Milk, https://www.walmart.com/ip/Horizon-Organic-Low-Fat-Milk-8-fl-oz-12-Count/47094270? lucerne,nesquik are some good brands
If you are going to NY, DC should also be in your plan. We did NY and DC together in 4 days. There are trains from NY to DC. In DC, most places of interest can be covered by foot. You just need to reach National Museum Mall from train station.
This agency is good one. You can check reviews. East Coast Tours & Vacation Packages New York Niagara Falls Washington DC Boston - TakeTours