Hello Jim, I believe the following documentation should address your concerns.
https://www.paloaltonetworks.com/documentation/71/pan-os/pan-os/policy/external-dynamic-list.html
https://www.paloaltonetworks.com/documentation/71/pan-os/pan-os/policy/use-an-external-dynamic-list-in-policy
Note that EDLs support three types: IP Address, URL, and Domain
I believe in your situation you would want to use a URL type EDL in a security policy rule. Otherwise, a second option would be to create an address object group which contains multiple FQDN address objects.
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