I'm not sure if this is the workaround mentioned in the linked thread, but I figured out a way to get each of the 28 bushings moved to the top-level assembly without extensive time spent locating each bushing. I used the transfer function to move the bushing from the lower assemblies to the upper assembly. Instead of all 28 moving, the bushing was deleted from all 28 instances of the lower assembly and only one instance of the bushing was moved to the upper assembly. This was my original problem.

I then used the duplicate parts function to make a pattern of the bushing and quickly mate the bushings to the same pins on which they mated in the lower assembly. I still needed to go through the assembly and select each of the 28 pins during the duplicate process, but it was still quicker than individually importing and aligning each of the 28 bushings.