How to assign a custom PCB layout to more than one schematic; deleting vestigial designs?

[Uberhund]

As shown in the attached screen cap, I have created a custom PCB shape to be conformal to its enclosure. I wish to use this shape for multiple circuit boards within the same Project for the same enclosure. However, when I attempt to assign the shape to a new schematic, Fusion360 responds with the prompt, as shown, that the board has already been assigned to other projects. 

What am I missing? Is there a way to determine which projects the custom PCB has already been linked?

If I knew which circuits were blocking the assignment, I might delete them. However, Fusion360 responds with "this file is referenced by others" when I attempt to clean things up. 

Is there a way to determine which files are blocking the new assignment? 

Is there a way to delete obsolete designs?

Many thanks to the forum for your thoughtful responses and constructive ideas

[jorge_garcia]

Hi @Uberhund,

I hope you're doing well. What you can do go into you electronic designs that use it and break the link to the 3D PCB. This will free the file so that it can be linked to new 2D PCB files. Easiest way to check what it's currently linked to is to try pushing to 2D PCB and see what file it pushes to. Obviously don't save the changes that are caused as a result of the push.

Another option is to save a copy of the 3D PCB and then try associating the files to new designs.

Let me know if you continue to run into problems.

Best Regards,

[Uberhund]

Excellent response, as always, Jorge. I'll give this a try.
You're the best!
Uberhund