What kind of dogs are these?

Hi, I'm a first time dog owner, and I just bought these dogs - the previous owner said they are a shih tzu / chiwawa mix, but that can't be right. I was hoping you could help me figure out what type of dog they are so I have an idea of how large they will grow to be. They're brother and sister.

They are way too young to guess their breed mix, they'll change a lot in the next few months, in fact they look way too young to be away from mom, do you know how old they are? What makes you think they can't be shih-tzu/chihuahua mixes?

puppies' breed

Hello, The lady said they were 8 weeks. I don't know.
They do eat puppy food. I think they are something else because they are not fluffy, their hair is very short...I have no idea! First dogs in about 35 years!!

8 weeks should be fine then, they just looked younger to me! Weird things happen when you mix breeds, sometimes they look so much more like one parent than the other. My dog has medium length hair (like golden retriever length) with long hair on the tail and ear fringe but both his parents were completely smooth coated! I wouldn't have guessed shih-tzu since their muzzles seem to be a normal length and they don't appear fuzzy (hard to tell in photos sometimes), but Chihuahua seems possible, or a small terrier like a rat terrier. But once they grow up a bit it may be easier to tell.

Good luck with the cuties! I can't imagine trying to do two at once!