I'm not sure how exactly I managed to do it, but I was able to show our great dane, pitbull and two cats that the chickens are part of our family, and if anything should happen to them, the offender will be in a great deal of trouble! The biggest thing was that the chicks were never off-limits. Our great dane is very spiteful and headstrong, and takes offense when he is not allowed to do something or see something. The animals were allowed in the room where the brooder is kept (under supervision). I would hold the chicks and make them available for sniff-and-greet. I tried to help the animals make a positive association with the chicks. Even my outdoor cat who leaves us a little furry or feathered "gift" every day will just check them out then walk away. My other very lazy kitty loves when I brood chicks because she likes to lay under the heat of the lamp. There's something in it for everyone!
As the chicks get older I'll let them run around on the floor, one at a time. I'll allow the cats to come up face-to-face to say hello. When they're ready to go outside they're allowed to mingle with the dogs and our outdoor cat.
For our situation, it was important to show our animals the same amount of attention as the chickens to avoid jealousy. I tried my best to treat them as equals, and it has worked well.
Good luck with your blended family!