What dog to get with my current dogs

Question
Hi, I'm sure you've heard from me before, i have a 3 year old lab retver, a 2 year old male jack russell terrier and a 8 month old female boston terreir all are altered the little boston is going in this coming week for her spay. Next year I have got my mother to agree apon another small or very small dog, I am now stuck between a Female Jack russell terrier and a Female chihuahua...I am unsure which would be a better fit I love both dogs I as stated above aheva  JRT now and my sister who lives near by has a chihauhau he is so sweet and tiny. I wa hoping you could help in determaning which would be a better fit, thanks and happy holidays.

Answer
I have had combinations of different breeds, different sizes, and just about any other combination you can think of.
If you have a very small dog, a Great Dane puppy can be overpowering. Puppies play and sometimes if the puppy is much larger than the adult dog, the puppy can be rough enough to give the small dog some discomfort, but generally, get whatever you want.
I have dogs now, ranging from a very small Yorkie ( 10 pounds) to a large mixed breed weighing 70 pounds, and 2 of different sizes between those.
They get along great and play together a lot.
Charlotte