First thing I noticed is how happy and healthy your dogs look! You must be taking very good care of them.
I almost did the same thing as you. I went to a pet store to get some new dog toys and I saw the cutest little puggle. I felt so sorry for it in that little window. He was sweetly chewing a toy and it hurt me to see him in what seemed like an aquarium style display. Luckily my daughter was with me and dragged me out of that store. I also wanted to check a couple of weeks later to see if it was still there but I knew if I did I'd be weak and bring it home. I called the store and asked where did their puppies come from and the store clerk told me they came from a puppy broker. Not good. Didn't do it.
I get it about the wanting to know their heritage. I have a mixed breed dog that was sold to me as a French Bulldog, Louie (Pennysaver ad and no papers-a double no no). Soon after I got him a companion a French Bulldog named (Toby) who did have papers. Well they were both 2 months old and as they grew I became aware that one was looking so much more like a Boston Terrier. Now I realize that he looks like a mix of both Boston Terrier and French Bulldog which carries the designer name of Frenchton. He's 3 now and just as cherished as my other dogs. Although I'm a little curious to know more I don't feel it's worth the cost of finding out. BTW Frenchtons are very GASSY!!!! YIKES!!!