A couple comments: has a doctor suggested that the cause of your child's skin condition may be caused by an allergy to cats? If so, you can board the cats somewhere for a couple weeks to see if not having them around helps. Also, you should be clear with your husband that the SPCA or any other animal welfare organization is unlikely to take the animals, so if he wants to surrender them somewhere it will likely be to the govennment AFCD, where they will almost certainly be killed, within a few days. Knowing that he is taking them to their death, and not to some great place that will care for them until a nice new home is found, may make him think twice - and he at least should understand the implications of getting rid of them.