My DB's family acquired a lab puppy about 16 months ago - gorgeous chocolate girl who is now grown-up in size but still a bit puppy daft in nature, as you would expect 
My DSiL was involved in dog rescues in the past, her previous dog was one from a Spanish Rescue who took in Spanish street dogs.
I am shocked that she is now talking about wanting a litter from her pet. She's got it all worked out in her head: we'd take a put, my parents and her parents (all people in their 80s) would take a pup each and she'd find good homes for the rest… 
No.
I don't want a. a lab, b. a pup bred for no valid reason other than her gratification and c. I cannot understand that she would want to knowing what I assumed she did about superfluous puppies etc…
There's nothing I can do, is there? 
I have alread very firmly said that I have NO interest in any potential puppy of theirs.