From one eldest to another, thank you for being strong. Thank you for sometimes being the woman and mother you didn't have to be. When you're mistakenly called 'mom', thank you for taking it in stride. It can sometimes feel like the highest compliment or the saddest loss of girlhood.

Thank you for trying to watch out for everyone and considering their feelings, even when it means you ignore yours. Very soon, you'll need to learn how to cope with the...