Print Project custom attributes on Purchase Order?

Each of our projects can have different insurance requirements/thresholds and/or warranty duration that need to be included/communicated to our subcontractors/suppliers on purchase orders. I have created the necessary fields using “Attributes” and then I added these attributes to the Projects (PM301000) screen as user-defined fields through the Customization>“Manage User-Defined Fields” prompt.

Now, I can also add these attributes as user-defined fields on the Purchase Order screen, but they just appear again as blank on each PO form and it doesn’t copy over from the project.

In Report Designer, I can edit the Purchase Order report to print the user-defined fields that I added to the Purchase Order screen, but is there a way to link/relate the Purchase Order back to the Project such that I can print on the the user-defined fields from the Projects screen instead of from the Purchase Order (so the attributes only need to be filled in once and are then copied over to each PO if the PO has a link to that project)? 

It might be important to know that we have the “Require Single Project per Document” preference in Payables unchecked (mainly because we can get AP bills that are allocated across multiple projects), but our POs are almost always only for 1 project (or else there’s 1 project and some portion to project X, but never 2 valid projects on the same PO). If there’s a non-X project on the PO, I’d like it to print the attributes for only the project and disregard X.