My Pyrs will bark and guard the fence line, but if someone comes close they'll stand up and try to coax the person to reach over and pet them.
Like you with Dutchess, I've only seen any of my pyrs take an instant dislike to someone a time or two, ever (and in both cases I agreed with her assessment of the people, too). Other than that, they've loved all of the people that they've met. The fact that Dutchess likes everyone, is gentle with your grandkids and the puppy, and is very friendly to humans while on leash and through the fence, sounds great. I agree with everyone that is just sounds to me like she's protecting her turf from other dogs, and that would be very, very normal for a livestock guardian breed. I think that if it were me, I'd just concentrate on taking her out on leash for more experience meeting other dogs and I'd only correct her fence guarding behavior at home if she attacks your other dog(s) while riled up from scaring off the "intruder dogs". Teaching her the "leave it" command would be a great help for that, I'd think. Please post pics of your pups when you have a chance, I'd love to see them.
BTW, welcome to BPO! I'm the mom of 3 human kids, 3 dogs including Daisy our Golden/Lab, Cassie our Pyr/? mix, and Sammy our Pyr. We've been loved by Cara & Halley, our Pyrs that are at the bridge now.
Modified to add: I just mentioned this to my husband and he said that if your husky isn't barking or helping Dutchess scare off the "intruders", Dutchess may be acting out at him in irritation b/c she feels that he should be helping her. Since this is such an ingrained behavior in a Pyr, she may not understand if he doesn't seemed to be concerned. Just a thought....