Hmmm, I’ll take a stab at some advice from the perspective of a mom and a little sister:
Listen to them. Their voices are smaller and younger, but I bet they have a lot they could tell you. Take the time to listen to their funny story of how their day was.
Include them in a special outing. It was alwaysa special thrill when my big bro would drive me to the 7-Eleven for a Big Gulp…his treat! He even took me out for an ice cream once, and it was my first time on a city bus. I’ll never forget that time
Get to know their friends. Their friends are special to them, and will give you an understanding of who your siblings are. Knowing their friends will also help in understanding the siblings fealings when they fight with their friends.
Be ready to give strong moral advice. You don’t have to always be the best friend. Younger kids will turn to the older bro or sister before the parent when they have an “embarassing” question. If its a question that needs parental guidance, encourage your sibling to go to the parents or at least inform your parents of what’s going on (not all things are tattle telling).
Don’t always be quick to shoo them away. One or two minutes of talking is great followed by a request for your privacy. “its been great talking, but I need quiet time for homework, etc” can be a nice way of getting the younger one out of your room.
The best thing you can do though, is to keep them in your prayers and ask them to pray for you.
You sound like a great older brother! Your parents must be proud.