Our photography business has clients that come for different reasons...newborns, professional headshots, Boudoir, High School Seniors, families etc etc

I am just starting to use Zoho to build our database (of almost 16 years), and if a jane doe comes with her high school senior, and then wants to come back for Boudoir, how would I build them into the CRM?  I dont want Jane Doe in there more than once, but if I want to send a mailer to all my Boudoir clients, how do I ensure she is included in the list, if she is in my database as a high school senior client?

It's kind of convoluted, but again, I want them to be in the CRM once, and track all conversations and business, but from multiple sources, and still be able to parse them out into one specific segment at a time, as needed.