Combining Image Target with Scanning Object

Hello!

I'm trying to combine two different targets (Image Target and 3D Scan) in my Unity application. Basically, I want the 3D scan target to augment a circuit board and breadboard, and the image target to track a complementary component (e.g. photoresistor) as the user places it over the breadboard. The idea of the application is to guide the user into placing a few components in the correct position on the breadboard. I can get each target to augment their parts individually, but the problem comes when I try to position the image target over the object target. The breadboard/circuit augmentation board often starts to jitter and rotate, losing its position drastically. I imagine this is due to the image target blocking the view of the breadboard, so the AR camera loses it's tracking of the breadboard? Is there any way I can keep the object target's position even when it's obscured slightly by my image target? Any other recommendations? Any help on this issue would be great.

Thanks