How to add supplier contact to supplier address

Hi Team,

We want to start sending PO PDFs to suppliers, however the contacts do not appear on Non Catalog Request section in dropdown.

For that we need to assign every contact to an address associated with the site, right?

Now we have 4K supplier contacts who are not connected to an address, and hence we need to do manual assignments, what is the best way to do that.

Thanks,
Avijit