Thanks Spikey, I'll keep all of that in mind. She's a bit of a know it all so of course she's correct in thinking a cross will avoid the breathing issues
At this stage I've tried to gently explain about the lack of genetic testing in cross breeds and the lack of knowledge of bloodline. I think my next plan of attack will be on the training front - they live in a duplex with a small courtyard, so I'm assuming it's going to be an inside dog, and from the small amount of research I did when looking at beagles I can't see that being a good mix.
I feel bad because a few years ago I would've been on board with her, but reading so much on here about puppy mills has opened my eyes and made me completely change my stance on cross breeds. I don't want to make her feel awful, but I hate the idea of these things being further supported.