Hello from sunny Arizona

Being a first-time chicken owner I could make a list of "Thank yous" for all the help you folks have been to me already, so let's just suffice it to say thank you all for being you and for being here with answers to all of my questions before they're even asked!

I have 3 RIR and 2 Leghorns who are of laying age and am enjoying 5 eggs almost every day (started out with 8 but my dog got 3 a couple weeks ago)

We didn't want just 5, so my son added 6 chicks to our count; then a neighbor 'dropped off' 9. Now I have Black Alstrlorps, Golden sex-links, Buff Orpingtons, more leghorns and my pre-existing 5!
I see some building and more innovation in my very near future. I'm sure caring for 20 won't be the same as caring for 8 was.

One concern I have is that a reliable source recently told me that I should "never" introduce the little ones to the bigger ones, as there is potential danger there and I'd have to constantly watch them. Does anyone with experience have thoughts on this? Ideas on how to intermingle them safely?

Welcome to BYC! I'm glad you joined us!

First keep your dog away from Chickens. One or the other has to be kept in an enclosed pen with roof, for safety sake. Chickens have never killed a dog. Second you have to carefully introduce new or young chicks to your established flock. There is a pecking order among chickens and it can be quite cruel. The best way to integrate is through the "Look but, don't touch "system.

Every time you add new birds or someone "drops off " more for you, they can be exposing, diseases or worms, mites, etc. to your flock. New birds should be isolated for a month or so before. "integrating them" to your established flock. Also taking in every one else's birds they don't want any more - you can end up with a huge population of birds you don't really need or want. It's easy to get overwhelmed by too many all at once.

Welcome to Backyard chickens.

You've already received some great advice so I'll just say hello, thanks for joining us!

Hi and welcome to BYC. In addition to the advice given, you may find this link useful

https://www.backyardchickens.com/t/1069595/introducing-chicks-to-adults#post_16276224

Good luck

CT