Modelling one-to-many relationships with content types So I'm trying to build a web app, and I've got it set up so far to have two content types, "Client" and "Client Contact".

Now the schema I've put together makes a one-to-many relationship between client and client contact, i.e clients can have one or more client contacts, and each client contact can be associated with only one client.

I'm trying to model this relationship through Drupal 7's content types, but I can't seem to find a way to do it. I thought it could be done through the 'existing fields' section of the 'manage fields' tab on the 'content types' page, but it doesn't seem to work.

Is there any way this can be done or do I need to download a separate module to get it to work?
From my understanding of your question,I think you need to use Entity Reference