To the best of my memory the side trip to Macau is an option but they become very suspicious very quickly when it is repeated. Female thais entering hk alone are often taken aside for questioning by immigration and that can waste up to 2 hours. Your simplest option is to go to immigration dept in wanchai and ask for an extension of stay by showing she has somewhere to stay, funds to facilitate the stay, your financial support, and no intention of working. Should take less time than going to Macau and back. Feel free to pm me if you want further info