I know this isn’t technically photography related, but it is still very much applicable in my life and may apply to yours as well. I am also not, by any means, a dog trainer. This is just what I have researched and done for my family and dogs and has worked amazingly for us. Bringing a new family member home is tough to communicate to a dog beforehand. I've had friends have babies and have their perfectly housebroken dog protest by having accidents everywhere and making messes. Luckily we haven't experienced that with any of our dogs meeting any of our kids, and this is what we did:
Before we had any kids, we had Indy. We got her as a pup and she turned a year old just before Jones was born. It was important for me to do my research and figure out the best way for baby Jones and Indy to meet - especially coming from a point where Indy had been the “only child” and was used to all of our attention. And on that note, was a bit of a trouble maker with high energy. Something that I didn't want to be a problem for meeting the newest member of our "pack."
The first thing we did (and have done with all the dogs and future kids) is drop off my dog(s) at my parents house when we go to the hospital to have the baby. Our dogs are pretty social (and Scout has a bit of separation anxiety from getting lost) so they do better away from us when they are with people. We have them stay with my parents for anywhere from a week to a few. This is more or less to help with us adjusting to newborn life as well as introduce them slowly.
The first thing I do once having a baby is greet my dogs by myself without baby. They're happy to see me and I give them all the loves. I'll usually have a blanket or something baby has used for them to smell while still giving them attention. The next thing we do is bring in baby in his car seat and let the dogs observe him in a confined space for awhile. (This part totally depends on your dog and their personality and if it's their first baby) When it was just Indy meeting Jones, since she was one year old and still pretty hyper, we left Jones in his seat and let Indy get used to him during our first visit. We let her sniff his feet and take in his smell/also see that he was just a baby.
After that initial meet we would start our greetings with me without baby and then have someone bring me baby once the dogs had calmed down from their excitement of seeing me. I'd hold baby while petting them and giving them plenty of attention. After no time the dogs didn't act like it was a big deal that we had a new baby. In fact, I think they thought the baby was their new puppy. With each kid, whenever I'd sit down to nurse Indy would come and sit upright at my feet and "inspect" everyone who came up to us.
Having a baby also had an unexpected, positive outcome on our dogs, in that with each baby, the dogs became more mellow. Which proves itself to be one of the best things that can happen, come the toddler years. When Indy was just a pup before Jones arrived, she was the biggest stinker (to put it nicely.) She would randomly decide to "attack" - playfully, but still, jerk moves. She also only liked to by cuddled on her terms - now she's the biggest pushover with the boys. They sit on her and cuddle her and use her for a pillow and she lets them. When the boys are learning to crawl she plays with them by moving her tail across the ground for them to chase. Things that she would've NEVER let me do when it was just us.
Like I mentioned before, all dogs are different, and who knows, maybe they would've acted exactly the same had we just brought them home the same time we came back from the hospital, but I like to think that this slow introduction (that has gotten quicker with each kid - since it's no new news) helped them realize that they are still loved and still part of the family, we just have a new "puppy!"
(Enjoy some pictures of Remmy with Indy and Scout)