There's a shelter here that passes out vouchers for the spay and nueter but it's all on paper!!
Several years ago, in queenscoopalot's and another friend's neighborhood (we're talking about a 6 block circumfrance or more) there were posters for a male cat to mate with the posting woman's female cat. She wanted her daughter to witness the miracle of birth ON Christmas so started posting around the neighborhood at the end of the summer. Well, come to find out, the female cat had been adopted from the shelter of vouchers (ok, I've said it before, I'll say it now- Northeast Animal Shelter). The woman obviously never honored the voucher. We went to the shelter to report this and they said they'd send the dog officer to her house to remind her of her duty. In the meantime, we tore down every poster we could find! (turned out too, she lived in the same bldg. as our mutual friend!).
Anyway, point being, you're right, it's best if they spay and nueter before hand! Is Mary Poppins a good girl! She adapted to family life ok? She has another chance now and I do wish you the best of luck with placing her! She is gorgeous and you are a true rescue remedy- so to speak!!