Add more targets and 3D objects

Hello,

I recently fired my developer, so I'm kinda stuck.

I know how to add targets into Target Manager, and from the project, I can see the 3D object that would be loaded once the camera recognises the target. At this moment, I have 2 targets, and 2 3D objects. My question is, how do I point a target in the Target Manager to a 3D object within the project? Essentially, I want to add 20 targets for 20 3D objects.

From the Target Manager, I can see the name and Target ID of the target. Do I use that somewhere in the project?

Hope to hear from you soon!

Thanks!