I am working through an old collection of recipes from my mother and came across one for oatmeal cookies. The problem is, all the dry ingredients are listed (brown sugar, flour, oats, spices, etc) but the only wet ingredients are 2 eggs and vanilla. This results in a super dry batter. I looked online but each recipe has different wet ingredients: water, oil, milk, butter, etc. Which one would be the best and in what amount?