We have added the musicians based on a picture posted by Tony Saunders to Facebook, identifying them and stating that the picture is from one of his first shows with his dad and Garcia, at the Inn. It is not 100% certain that these facts attach to the May 31-June 1, 1974 shows, but it seems very, very likely.
listing: "Van Morrison Sets Lion's Share Shows," Marin Independent Journal, May 31, 1974, p. 22. Note that a picture of Merl accompanies this set of entertainment listings. So, while Jerry was not announced, this billing was brightly spotlighted.
listing: San Francisco Examiner, May 31, 1974, p. 30