You have 3 dogs now? What do you think your monthly dog food bill is?
Technically I only have two dogs. The other two ( feist and great Pyrenees ) belong to the neighbor. But they hang out with us as we are here and they work every day. Dexter the great Pyrenees is in love with a German Shepard a couple of miles down the road and is hanging out with those folks . He has not been back in over a week. That is part of the reason that we got Elly May now. To look after the other critters we have here. I am not really that concerned about the food costs but am guessing that I spend about a couple of hundred a month for animal food ... dogs and cats..... chickens I don't count in that equation as they give us eggs in return.
DWC Finnigan ( My GSD ) is with me 24 / 7 when I am not working on the coast. So we took him with us on the 3 hour round trip to pick up the puppy. He sits on the back seat of the truck and the admiral had the puppy in her lap on the way home.
Expect there to be the odd bark and growl when the newcomer is put in its place. But that is normal behavior and will set the hierarchy for the future. Puppies seem to have a " shield " of innocence that prevents adult dogs that are of sound mind from hurting them.
So yes, when she tried to eat his food ( with she is not supposed to do anyway as she gets puppy food ) he will growl and even snap at her. But all without actually hurting the pup. Outside, she just follows him or at least tries to keep up with him.
So don't worry would be my advice. If your dog like riding in the car / truck, take him along and meet on ground that is not his would be my advice.