Boil eggs until hard boiled. Remove from water and refrigerate until cool. Cook pasta according to directions. Rinse and set aside to cool. Cut chicken into bite-sized pieces. Finely dice onions and celery. .Peel cooled eggs and chop. Add eggs, pasta, onions, celery, chicken in a large bowl. Add salt and pepper. Take 2 cups of mayonnaise and whisk 1/2 cup milk into it, making it 'pour-able'. Add to the bowl with other ingredients, and fold in thoroughly. Do the same with the remaining mayo and milk. Season to taste. Cover and refrigerate until chilled. (best overnight) When the salad is chilled throughout, it is possible that it may need to be re-seasoned, Occasionally, the salad absorbs the mayo, so a bit more may need to be added to restore its creaminess.