Adding them to the reservation as long as they don't exceed room capacity is not lying, nor is it skirting the rules; in fact, this very thing was suggested to us last year by the desk manager at BC. My sister and her two daughters were not staying with us, but wanted to visit us at BCV for a few hours before they flew home. I asked at the front desk if they could swim with us, and the manager said that we had room to add them to the reservation so suggested we do so in order to get them keys. In fact, he even did it for us.