There's a special kind of chaos that comes with adding new chicks to an established flock, and our friend here is living it. Ten chicks already, and now five more? That's not a backyard, that's a feathered mosh pit waiting to happen. The good news is that the young ones usually have a much easier time of it than the adults. When everyone's still in the awkward, squeaky-voiced phase, the pecking order isn't so much a rigid hierarchy as it is a suggestion scribbled in the dirt. At that age, they're less "get off my lawn" and more "oh, new friend? Let's inspect every single one of your feathers."
The real question here isn't whether the new chicks will be accepted; it's whether your current crew is past the point of being territorial. Chicks under a certain age are basically tiny, feathery sponges for new experiences, and they're far more likely to see newcomers as potential buddies rather than threats. But here's the catch: just because they're young doesn't mean they're automatically gracious hosts. Chickens are fowl-weather friends, after all. The moment a newbie looks a little different, or moves a little slower, the pecking starts. It's not out of malice, it's just how they sort out the guest list. So, yes, you're probably fine, but you should still expect a few days of dramatic squawking and some serious side-eye from the original ten.
What we'd tell you in person is this: don't just toss the new five in and hope for the best. That's how you end up with a chicken version of a reality TV fight. Even if they're all young, give the newbies a safe zone, a separate area where they can see and be seen without getting chased. Let them mingle for a few hours a day, then give everyone a break. And for the love of all that is cluck-tastic, add some extra food and water stations. The quickest way to start a brawl is to make everyone share the same bowl of treats. It's not about whether they'll play nice; it's about whether you're giving them a reason to.
Our honest take? You're overthinking it, but in the best way possible. The fact that you're asking means you care, and that already puts you ahead of the game. The dynamic will be messy for a bit, and that's fine. A little squabbling is normal; it's how they figure out who runs the roost. But as long as you're patient and give them a little space to sort it out, you'll likely end up with fifteen birds that couldn't care less who arrived first. Just don't be surprised if, a month from now, the new five are the ones bossing around the old guard. That's just the circle of chicken life, and honestly, that's half the fun. So, get your extra feeder ready, brace for a few ruffled feathers, and enjoy the show.