@Isabella266
guests are divided into adults, infants 0-2 y.o. and children 2-12 y.o. so you cant set it to 5+ y.o.
you can say it in your description and your house rules but we all know guests don't read. Even if you turn off the instant booking you will still get requests for 4 adults or infants and if you decline too many requests you will be penalized.
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I would suggest to set your listing for 2 adults and don't mention your pull out sofa at all to prevent smuggling unregistered guests and infants