Let me begin my saying that I too have 2 "Morkies" Yorkie/Maltese mixes. But unlike you mine are both rescues. Doodlebug was a puppy when I brought him home from the rescue. His mom was purchased at a puppymill auction and he was born at the rescue. Bogey is also a Yorkie/Maltese mix and from a shelter. He was a little over a year old when be became part of our family. Although they are both Morkies they are as different as they could possibly be. Bogey is blonde with dark brown eyes and a silkie coat. Dbug has black eyes and an almost white cottony coat. When you mix the two breeds you never know what the end result will be. Now we add your little Belle who looks nothing like my two. She is adorable but now we are adding another color combination to the Morkie "breed" with her black and white coloring.
There is a breed standard that all reputable breeders adhere to when having a litter of puppies. They do not just throw together a male and female and hope for the best. When someone breeds a mix that is exactly what they are doing. Hoping for cute puppies. But truth be told there is no way to tell what the final look of a puppy will be. Perfect example would be to just looking at all 3 of our Morkies the variation is huge!
I think the question would be other than the money factor why is the woman that breeds Morkies and sells them in the local paper doing so? The only reason is money~unless she gave you Belle for FREE that is her purpose. Someone is willing to pay her $$$ for these cute puppies so she is filling the demand. But really all that is doing is making her a BYBer earning a buck of her dogs. Then add to that she just uses the females for 2 yrs worth of puppies and rehomes them. To me that is just very sad. They are only her money making machines and when their time is up off they go and the next one is put into its place

What you described in a BYBer and someone that I personally would not only not purchase a puppy from but also not recommend. It doesn't matter if you have a 2 year health guarantee or a forever return policy. I wonder what would happen if someone tried to collect?
Reputable breeders take two pure bred AKC registered dogs with the best qualities to try to achieve the perfect specimens of that breed. Someone who is mixing to make puppies could not have high quality dogs since a good breeder would never allow that to happen with their lines. I personally would want to know where her dogs came from to not have a spay/neuter contract in place.
There might have been a time that I would not have thought it was wrong to purposely mix breeds to make puppies. But in the past few years I have become very aware of all the dogs that are produced in this country and are PTS every year. Our shelters are over run with abandoned and unwanted animals.
Like I said before, I believe that if you want a Morkie you should adopt from a rescue or shelter. I do not feel that any of my three are inferior to other members pups on YT. Some of the best show breeders in the country that are right here on YT have told me that my dogs are pretty. I know they are not show quality but they sure are not any different than many of the other Yorkies and mixes on this forum! They are loved and care for unconditionally just like the love they bring to my life. There are plenty that need home and are dying because they do not have one. I truly hope that you take something from my words today regarding ethical breeding practices. This is the way that I learned to love the breed and support responsible and ethical breeding practices.
Here are pictures of my boys~
Doodlebug is first and Bogey is second.