Is there a way to make Global BPAs Read-Only for Buyers?

If Global BPAs are to be managed by a Corporate Procurement team, providing access to Buyers to source from them, how could you secure them so they are only Read-Only for Buyers? (e.g., Buyers cannot modify any attributes only on Global BPAs)

Is setting document security for Purchase Agreements in the document types the only option? Or can this be done by controlling access with a Buyer's responsibility? OR can this be done via a Personalization?

Please provide options along with pros & cons to each.