Well GOOD ON YOU for giving those two wee girls a home. Please keep us informed as to how they are doing.
As to the dogs.... Slow is the thing. They will be sooooooooooooooo excited at these new, differently smelling, and wee creatures. They will all come to know and care and protect one another, but for the first couple of days, just take it slowly. LOVE the doggies. Just be watchful. They can hurt when they don't mean to.
I really don't think there will be any trouble. I too have had dogs and cats and horses (and fish and birds and hamsters and guinea pigs and goats and turtles and and) all my life and, frankly, have never taken any particular care when introducing new ones. And also never had one injured. But it is always wise to be a little careful.
Animals always recognize babies - of whatever species - and tend to react accordingly. Just watch them. It's something new. And dogs are so 'olfactory'. Hold the new babies close to you and let the doggies sniff them (briefly. Don't want the kittens upset either!). Maybe keep them apart for a day or so - while yet taking time to 'introduce' them - letting the doggies smell the kittens next to you. But, you know, I seriously expect the bigger 'trauma' will be for the kittens. They need to be introduced to the dogs as much as the dogs to them.
But (you don't need me to tell you this!) in an astonishingly short time, they will all meld into one huge happy family. In my childhood home it was a Doberman (rescued from abuse), two cats (my Mum's Blue Boy and my Muff) and my rabbit (my Father's next most favourite animal. His favoiurite was the hamster. Never knew why!) all playing together on the livingroom floor.
Warmest of welcomes to Saffie and Skye!