@Alicia753. Alicia, my understanding is that infants count as a guest, you just cant charge for them. Did Airbnb change this policy?
@Nicky253, depending on which place they are staying in, I would try to cancel (if you want) on the basis that it may exceed the maximum capacity (is it the one with 7 or 8?).
Last year I had a request for 4 adults, 2 kids and 2 toddlers, which was 2 over my 6 capacity, even though she tried to argue she was able to book for this many so it must be ok (thank you Airbnb!). I said no room (its a tiny cottage and third bedroom is bunks and no room for a cot in 2 of the 3 bedrooms anyway). Luckily I dont IB and I was able to head this one off early. There was even an option when I declined to say it was over capacity.
If you want to cancel them I'd argue that it exceeds my insurance policy capacity numbers. We have strict emergency laws for guests, so like hotels we need to be able to advise authorities exactly how many are staying.