Getting a second dog.

We have allowed Kiba (our dog) to sleep in our room at night as when we first got her she did not cope being alone at night (she is still a little scared of the dark). She is 4 and a bit now, we got her when she was 3 (rescue dog). In every other way she is fine, well trained etc. Any of her old bad habits we worked hard to change except she is a bit licky, but we accept that is part of need for re-assurance (part of being an abused rescue dog).

Now this doesn't bother us except that now my wife is pregnant and we'd like to move the dog out of the bed room, preferably to downstairs at night.

I am thinking
1. we need to do it now so she doesn't associate that with the coming of the baby. (along with any other changes).
2. Getting a second dog so that she is not alone at night, ie. "that she is still with her pack".

She does socialise well with other dogs, she is even quite tolerant of young puppies doing young puppy things.
Do you think this a reasonable / good idea ?
If so, would you recommend we look at much younger dog, a similar age dog, or a much older dog ?

My belief is yes, a rescue dog of similar or younger age and of similar or small size. My wife however is not sure.