When ever I have brought a new pup into the house, I tell my dogs "be nice,take it easy, it's a baby dog". All my married life I've always had four or five dogs,and the resident dogs have always accepted a puppy. I have also rescued two grown Malanois,and they did fine. I tried a 4 year old Frenchie rehome, but she had been an only dog-and SHE attacked my dogs, and I had to give her back. When I've brought pups home, I just always acted kind of matter of fact, and didn't make a big deal out of it,except if they got
too rough while playing with her. My dogs are all jealous of each other,as far as getting brushed or petted, but not mean jealous-I don't allow it. Sometimes they will fight over a toy-then I take the toy. You have got to keep a good eye on things, but don't act nervous, or make your dog feel left out. Best of Luck with your new baby! I would also have a "playpen" or crate for the baby, so that you have a time out area. Sometimes puppies are hard on the resident dog!!