R.T.
DO NOT feel you have to feed everyone a meal. Juice and water, for kids and adults if fine. Also, the kids won't eat much and parents will probably be feeding them and/or running after them, so finger foods for everyone is more than adequate. Be careful with cake (or whatever) you decide to have for candles. There are many options such as cupcakes, cookies. Have fun with the whole thing. One year is a mile-stone, but still so young.