The photo you have is a screenshot from a video taken before the formation of the Eagles, when Glenn and Don simply were backing Linda as part of her touring band. Bernie and Randy both had backed Linda at some point... Just not at that particular time.

However, she would also later occasionally appear as a guest at Eagles shows. One of these, a 1974 TV special called Don Kirshner's Rock Hour, still circulates. There are clips of it on the History of the Eagles documentary.