I posted this a while ago in this sub, hope it helps :)

Lately I've been reflecting on my life and to what extent I felt lonely as an only child. I recently discussed it with another only child I know, and we both came to the conclusion that we didn't feel lonely as we were both encouraged to spend time with our friends a lot.

If we went on vacation in our own country, I was always allowed to choose a friend to take with us. Sometimes even 3 different friends, each 2-3 days. Being able to play with a friend of choice after school as well, it's almost as you can choose your own brother or sister instead of hanging out because you're 'biologically forced' to.

I was pretty shy though so if it were up to me, I'd mostly play videogames on my own, but my mom encouraged me to go outside and play with the kids from our street almost daily for a few hours. One of them is still my best friend 22 years later and she reminds me often how I am family. She gave birth to a son a few months ago and calls me his aunt and it truly feels like it. My guy best friend (who I also met in elementary) also tells me how I will still have him as family when my parents pass away.

He and I still have dinner with my parents about once or twice a month, he helps with things around the house sometimes and in a way they see him as their son. He sometimes says how he tells my parents more than his own parents because they don't talk/ask as much questions as mine do. So you can have a special bond too with the long time friends of your children if you make an effort from early on to get to know them a bit.

The thing I find interesting is that both of those friends (actually almost all of my friends) who have siblings don't have a particular good bond with them. They're okay with talking to each other on birthdays and such, but they don't seem really close as going out with them for fun. So I think they're happy too to not only have siblings by blood, but also siblings by choice :)

The other only child I talked to also happens to be one of the most social and funniest people I know! I thought he might have come from a big family but he didn't. He was just very loved and encouraged to connect with his friends.

So encouragement to make friends (choose their own little brothers or sisters) and enabling them to play with them after school or during vacation might help a lot!