You can use the check in with comment function in Copy Tree and include in the comment the source file (i.e. "Copied from Top Assy.slddrw") . Copy Tree is more useful than Pack and Go when dealing with Source and Destination folders inside the vault. I also find this function to be useful at quickly identifying files that can't be checked in because of workflow or duplicate file name restrictions. Also, if your library components are stored in a different folder structure other than your project folders, they are not automatically selected in Copy Tree.
Kyle you could probably create a variable and link it to data card. Then if you do a pack and go you will have that previous filename variable in data card. Then when you check-in you could list in comment field what you copied from and have it in your history. Or probably could automate it with a dispatch script that could run during a workflow transition.