Yated Shidduch Forum 11/1/19: Breach of Confidentiality?

Question:
I have heard lately that along with the growing use of “shidduch groups” to network and share résumés and information about singles for shidduchim, there has developed a situation whereby many singles who meet a shadchan privately end up getting posted and mass shared without having granted permission. When they find out, they are very unhappy, but powerless to do anything, since by that point their information is already out there. What steps would you recommend a single take to ensure that their information doesn’t get mass shared without permission?