and its a party for a ONE year old! not a 4+ year old where you would have kiddy food and kiddy games etc... it is mainly adults that are coming apart from 4 other children aged....2x 2.5yrs old 8mths, and 6mths.
Then perhaps make it a verbal invitation so everyone invited understand what you want. I honestly don't see why you wouldn't want other children and you can still have "kiddy" food and games i did at my DD's 1st birthday.. but then its your party.