@Dave876 you can always send inquiries instead of a booking request, asking the hosts to pre-approve your booking if they will accept it. Then you can make sure everyone involved is on board before you actually book any property. Of course, you don't want to let any time pass between booking the properties.
Right now, in your shoes I would try again to contact the host who didn't respond, and at the same time, explain the situation to the host who did and ask them if they can possibly make an exception to their policy under the circumstances. Many would do that, if the dates are distant and the booking was made only a short time ago.