What a sticky situation! I think what I would do is continue to nonchalantly question her about the kitten. Then at some point when she seems a bit like she is complaining about it, say this, "it sounds like you've really got your hands full with 3 kids and now this kitten!" Maybe that will open up the opportunity for her to feel free to say how she REALLY feels about the kitten. If so, then that would be the time to offer to help 'her' out and take the kitten off her hands!

Let us know how it goes! GOOD LUCK!

Kim