As the helper, she is too beautiful already. Some are not beauty who also wear less to attract the man at home. Even the man doesn't mind, I guess the woman who must feel uncomfortable.
You install the web cam to record it. Then you employ the new helper. Until you see that new helper is OK, you call the police to catch her. If she needs to go to the court and has the black record, she can not come to work in Hong Kong again. The immigration department will black list her. If not, she can find the new job, it is very unlucky to the new employer.