How would you respond?

[Momof4]

I would respond with something like this: Dear .........., I am pleased to inform you that a space has become available in my daycare and I am interested in setting up an interview at your earliest convenience. Surprises do happen in my business that cannot be predicted and I hope you will contact me so that we may speak more about your family and your daycare needs and arrange a meeting.

You don't have to explain a thing about the other family or tell anyone about how and why you decide to run your business. Each family is expected to abide by their contract and privacy issues keep you from telling one family about another. Use that as your reasoning if they ask any questions.