Chihuahuas require a lot of care and attention. They are also extremely delicate and territorial and may not fare well in a household with that many small children. You would have to teach your children how to handle the dog carefully. Even if their intention is not to hurt or harm the animal, they may do so accidentally.
I would also strongly urge you to adopt one at a shelter. Perhaps offer to foster one for a few days to see how it goes. Like a test drive. You'll be buying time for an animal that might be running out of options.