Null Objects and Tracking in After Effects

[JPH71]

How do I set up Multiple Callouts to appear one at a time while each is Tracking Null Object?

I have the first call out title appearing and disappearing while tracking a null object containing all the tracking points of the video sequence. I need 4 additional call out titles to appear and disappear (2 at a time) while also tracking null object in the video sequence, but at differnt positions along the object. 

Is there a way to parent the other call outs one at a time to the same null object, or do I need a separate null object created for each additional call out? If I need more null objects, do I duplicate the first null object or do I need to start from scratch and set up new tracking points with each new null object? Thanks in advance for any answers or feedback! I appreciate it!

[Rick Gerard]

If your null is moving along the path you can shift + parent all of the call-outs to the null so that they snap to and are attached to the same position, then just set in and out points for each object. There is no need to overthink anything. 

If the comp is more complicated than that we need a screenshot showing the modified properties showing for the layers you are having problems with. Select the layers, press the U key twice, make sure the composition is selected in the Project Panel, Make sure that both the switches and modes columns are showing in the timeline, then take a screenshot and embed it using the toolbar. Do Not use the tempting but useless Drag and drop here link below the forum reply field. It's useless.

[JPH71]

Thanks for your help but the comp is complicated as I'm using call-out templates with their own precomposed properties. I've decided to try using the 3D Tracker Camera next and may have to do without the precomposed call-out templates if I can't get them to track that way either. I may be back with more questions! Thanks again.