Once an Oregon broker has established an agency relationship with a client can that agency relationship change?

Yes, the established relationship may be changed to disclosed dual agency if
the seller and buyer agree to let the agent represent both parties in an offer to
purchase

No, it would be a conflict of interest for the broker to ask the seller if he could
also represent a buyer in an offer to purchase

No, a change in agency representation would be both an ethical and disclosure
law violation

No, to represent both parties after representing the sellers exclusively would most likely bring about a reprimand from the Real Estate Commissioner