I am sorry to hear of your loss. It never is an easy decision to let our fur babies go.
As far as the other dogs handling the loss it depends on the personality of the dog, I think, and their position in the pack. When we lost Rocky, Rambo (dominant male) was upset, and mopey, but not too bad. We then got Bandit, who remained submissive to Rambo. When Rambo died, Bandit was inconsolible. He wandered and cried, stopped eating, had severe separation anxiety for the first time, until we got Raven. She became the dominent pack leader. We added Merlin without a further loss for about 2 years, then lost Bandit. Merlin and Raven were only affected for about a week, then they adjusted and were fine. Now I have three again, Raven remains dominent, but she is failing. I am dreading the loss of another dominent pack leader.
Stella