You know who did know the protocol? Their manager Peter Grant. Did he say anything? No, because he was an a$$hole.
You know who else is an a$$hole manager, Robert Stigwood. Rita Coolidge has long said that she wrote the piano coda for Layla, and Bobby Whitlock said he was there at the house with Rita and Jim Gordon (who were dating at the time) when she wrote it. She said that Jim Gordon had a 3 chord progression, and that was it, and so she wrote the melody, bridge, and lyrics for the song "Time" that they did together. She said she gave Eric Clapton a demo of the song that she and Jim did, and it was in front of all of the band that played on
Layla and other Assorted Love Songs, and he listened to it, and didn't seem interested. The band corroborated this happening. She left the demo with him. A year later she heard Layla on the radio, and heard the piano part she wrote, and she had given the song
Time to her sister and her husband Booker T Jones to do. Rita went to the record store to see if she got credit and she didn't. She called A&M records, her manager, Eric Clapton who made himself unavailable to her (not surprising), and then talked to Eric's manager Robert Stigwood. Stigwood asked her if she really wanted to go up against Stiggy (himself), and that she was nothing but a girl singer. She got screwed over.