Our dog Billie

Question
We have a Parsons Jack Russel called Billie, she is a delight.  First, some background information:  We had an Australian Terrier called Basil, who came from a rescue centre, he was found in a skip by builders.  He had diabetes and eventually started to go blind but such a character.  Towards the end of his life, we decided to get a puppy to be his friend and we chose Billie.  Basil was never too keen on her but they did everything together, I put them in the car every day and took them to the park, and although he couldn't see, Billie stayed near to him and she sort of guided him somehow if he needed it.  In the evenings, she would sit and wash his face and ears.  He always grumbled but if she wasn't there, he used to try looking for her which is why, we think, that when Basil died, nearly a year ago now, Billie became rather timid at odd things.  Billie is 3yrs old now.  My Son 19, husband 56yrs and Myself, 45yrs we all adore her.  She has beds in every room, a large garden which she has constant access to, I work from home and we make sure she is rarely on her own.  She comes in the car with me, standing in the middle, with her head sometimes on my shoulder, she loves the car,I drive her most days to see her two terrier friends in the park for an hour or so.  I do everything for her, however, she's not that struck on hugs or cuddles by me  but she adores my son, she sleeps in his bed, is content just next to him or being hugged by him. Every evening she climbs up on my husband in his chair and for about 15-20mins washes his face,and ears.  He doesn't like to stop her and then sometimes she falls asleep on his chest.  I'm making her sound soppy but she's really not.  She loves fireworks, the sound of gun fire, chasing squirrels (never got one!), adores other dogs and children. Is very gentle with food, when being given anything.  If a dog is aggressive to her, she just backs away. I just can't tell you how much we adore her.  My question (finally!) is we feel we would like to get a companion for her, either a rescue dog like old Basil or a new puppy.  she loves puppies, washing and licking them when she has a chance.  She has been neutured.  We could easily buy a puppy.  However there are so many unwanted dogs, and we have a good home for dogs, big garden, someone around all the time, comfortable lifestyle and even in this credit crunch society, our dogs would never leave us no matter what, they are part of us, but if I got a rescue dog, would Billie feel as though she was not wanted as much.  I'm not worried about the settling in of a rescue dog.  Kindness, steadiness and routine and love will sort that out, but in trying to get Billie a friend I don't want her to feel any less loved.  I know my question sounds rather trivial but Billie's feelings have to be considered in all of this.  Thank you for taking the time to read this, didn't mean to go on, kind regards Sally

Answer
Hi Sally,
It sounds like Billie has quite a great life!
Your question does not sound trivial at all, but very caring and very conscientious.
I wish I had an easy answer for you but truth is, you just never know when it comes to two dogs interacting. In general Jack Russells enjoy the dominant status so if you are going to get a rescue dog, make sure you pick a NON dominant breed, which will take his or her place nicely as dog #2 in the family. Definitely make sure the new dog is spayed or neutered and the most important thing is to make sure Billie doesn't feel like she's being replaced. You will need to give both dogs ALONE time with you and be sure to stop any aggressive behavior immediately if you see any. It's also important to make sure they spend quality time together as well. Make sure the new dog has his/her OWN bed, own toys, own bowls, etc. No sharing of Billies things right away. If and when you bring a new dog in, make sure to introduce them OUTSIDE on your lawn, not in the house, and have the new dog follow Billie inside. You will be establishing pecking order right away! Of course YOU will be the first one inside!!!
Lastly, try to make sure that if you HAVE to, you can bring the rescue dog back. Even the greatest owners and trainers sometimes run into a pair that just don't click no matter what!  
I wish you all the very best of luck!!
Take care
Carol