Birth Dates on Calendar

This is another reason why I'd love to have the ability right in CAS to distinguish more than just by an age bracket, the number of days between Sims. I create them in order, generally. But, if I make a mistake by generating genetically a Sims' mother, then she appears in the lot queue as the eldest Sim. Even though I created Jean as the eldest son, at one point he was in the third child spot. What's up with that? I like to age my Sims when I'm ready. The young couple I plan on putting together from the two families in my rotation save were in all actuality, nine months apart in age, he being the elder. That's hard to do in this game, to be sure. I generally make sure I age him up first, and then her to get it sort of correct. To be more accurate, I could wait three Sim days, since a pregnant Sim gives birth on the third day of pregnancy, which implies one Sim day is a month. (I generally get too antsy to wait that long with this couple. LOL).