I put a photo of Poppy on Facebook and a girl I used to go to school with commented that she wanted one and asked if I would tell her when Poppy's breeder was due another litter.
She has just had a baby a few months ago and is pregnant again so I dont think this is a good time to be raising a young puppy.
I tried to tell her in the nicest way possible.. all I could say was that they are really hard work and its like having a human baby, it would be very stressful. But she brushed it off.
With family I think it is easier.
I think its horrible that your sister simply "got rid" of her other dog, what if nobody picked him up? he could have been run over by a car or anything. So sad.
Your right there is no way she should get another dog, she dosnt sound responsible enough and its not fair on the dog.
I would tell her straight that it was cruel what she did with her last dog and that I dont think she is responsible enough for another.
But then again I know everyone has different relationships with their siblings and you may not feel as comfertable being so straight with your sister.
I do think you should try and talk her out of the idea though.
Tell her that size dosnt really matter and ALL dogs need training or they will drive you nuts. If she isnt prepared to train the first dog I doubt she will train a second.
Good luck!