You’ll always be first born among your siblings, but you are no longer responsible for their welfare. There was a time when you were responsible: when you babysat your brothers and sister you locked all the doors and windows. On family outings, you periodically counted heads just like your parents did. You were afraid of being separated in elevators (seven people is a lot to cross the threshold of automatic sliding doors, especially when four of them are younger than you and might not be paying attention). You come by your hyper vigilance honestly.
But those days are long gone. You get to relax. When family members are in the same room, you don’t have to direct traffic, conduct the orchestra, rally the troops, or rouse the sports fans. You’re all adults now. Nobody’s well-being depends on you except your own. Don’t have hurt feelings about it, enjoy it.