You could try to convince them to let you know the names/contact info for the new owners; then you could offer them advice/support with the pets for their lifetime. (Frankly I have never personally been successful with the idea, but maybe it's just me :-)). Kat Chaplin has a DYNAMITE set of guidelines for tackling calling free-to-good homes advertisers. She is "Neuteress of the Night," but I don't have her email or web address in my head just now.
http://www.ahimsatx.org/nnl/docs/HowTo.htm
How to Address Free To A Good Home Ads in Your Community
Is Kat's work. It is always worth the try. I know it's discouraging to think that 5 or 6 week old infants could be removed from their mothers and placed in homes alone, with no guarantee of accountability. Keep on educating though, Katie. We have to make the information available to those who will heed it!
Best,
Linda