Two dogs is always better than one. Three dogs is better than two dogs and so on. I think if we had the chance we'd have every single dog we wanted. I know someone with 18 dogs to date (her family own a lot of land and they are working dogs). It's always nice to see your dogs snuggling up together, or having a good game of tug and war - but of course, each dog is individual and you need to be aware of this when you bring your GSD into your home.
There are lots of things you should consider when adding a GSD to your family. Cost, for one. The most important question you should ask yourself, though, is "Would my dog be happy with another dog in the house?" No-one is psychic; you cannot tell how your dogs will react even if he/she is the sweetest dog on earth so you will not know until you actually bring your GSD home.
Dogs will always act differently inside the home than they act outside. My fiancé's father has a beautiful miniature boxer called Fudge. He is wonderful with dogs when they're out. However, trying to bring one into his house? Not going to happen.
I was quite lucky that when we brought Sky home Candy took to her straight away. However, this is not always the case.
It's generally known that the more differences between the dogs (age, sex, size, personality etc) the more the dogs will get on. Dogs have their territory and will fight if they feel threatened. The more differences between your dogs, the more they will recognise who is going to win a fight without actually having a fight.
If you are getting a pup you should be aware that pups always get on with other dogs. It will be frustrating when your pup pays more attention to your older dog than you but please don't worry, they're bonding. Just make sure you spend a bit more time playing with your pup so that you can bond too.
Introducing your GSD to your family
Introducing your dog into your family can take a good few weeks, so please do not give up after a few days.
Before your dogs actually see each other, why not introduce them to each other's scent. Use their bedding for this. That way, your dogs will be accoustomed to each other's scent when they meet each other for the first time.
Make sure they are well fed before hand. They will be content with a full tummy and much less likely to react aggressively towards each other. Feed them their breakfast in the morning, then give them their dinner 30-40 minutes before introducing.
Introduce them on neutral territory. Take them for a walk in a park where your dog does not usually go. Do not do this with a pup that has not had both its injections. Don't force them to interact either, if they want to ignore each other let them ignore each other.
If one of them immediately attacks separate them and try again later on in the day in a different location. If a dog is injured, you may find it best not to continue.
In your home, remove anything they may fight over: toys etc. Make sure they have their own bedding and put it in separate rooms until you know they are fine together.
This may seem obvious but avoid giving more attention to either dog. Don't get involved in any small fights, they will sort it out themselves. Dogs work on a pecking order; a leader will need to be established. If you are worried they will get into a big fight, keep them on a lead so you have control at all times.
Unless you are sure they are not going to fight do not feed them in the same room. With your new dog make sure you are able to stroke your dog, touch its back and take away its food bowl without it growling or attacking you.