new dog

Question
Hi, I have a 1 1/2 year old female spayed lab, and a 7 month old male unneutered jack russle terrier(planning on neutering him in a few months), I would like to get another lab, but am unsure if it will work, I don't know weather to get a male or a female(I'd perfer a female... just because lol) my lab is really friendly with my mums two shiz-tuzs which are spayed females also so I don't really think a female would be a problem with her, I just need an apinton on this, thanks for any help.

Answer
You have the combination least likely to cause problems.  Add a third dog of either sex, and you will have 2 of one sex.  If they are both highly dominate, there will be trouble.  2 females are more likely to be a problem than 2 males.  Whether you get another female or male, try to choose one that is a more submissive member of its litter.  Explain your needs to the breeder.  In general, problems are the exception, especially if all the dogs are spay/neutered.