What albums can you think of that have one or more members of the band on the cover, but not the whole band?
Here's what I can think of:
Chicago, HOT STREETS - 5 of the 8 members are visible on the front. (The rest are visible on the back, along with one of the guys from the front appearing a second time).
Doobie Brothers, STAMPEDE - 5 of the 6 members are on the front. (The 6th apparently didn't join until after the cover photo was taken).
Doobie Brothers, TAKIN' IT TO THE STREETS - 1 member of the band is seen, in a closeup of part of his face. (The full photo is in the inside cover.)
Doors, ABSOLUTELY LIVE - 2 members (out of 4), or just 1 on the CD reissue cover.
Fleetwood Mac, HEROES ARE HARD TO FIND - 1 member (out of 4)
Fleetwood Mac, self titled - 2 members (out of 5)
Fleetwood Mac, RUMOURS - 2 members (out of 5)
Fleetwood Mac, MIRAGE - 3 members (out of 5)
Renaissance, ASHES ARE BURNING - 2 members (out of 4). (Other 2 members are pictured on the back.)