The man to the far left is probably no older than about 35. The older couple say 60, the girl probably no older than 15. The woman on the far right is hard to gauge. There are resemblances here. The far left man and the girl look like father/daughter or brother/sister. Couples did not always pose together, at least in old US photos, but this photo looks like it may be
Italian? Customs could have been different. Deference may have been given to the older couple to be in the middle, more or less, in which case the others could not have stood together as a family group, even if they were. The older woman may look like the younger man. Her eyebrows are washed out by the light and you see the line of her eyesocket. If you imagine her with visible eyebrows, she could resemble the younger man, particularly in the eyes. The older man doesn't particularly look like any of the rest, which isn't significant. If you have other photos of close relatives, maybe more could be determined by comparing faces. If I had to guess, I'd say the far right woman is the wife of the far left man. The girl is arm in arm with her in a mother/daughter way, more so than sister/sister. It would also be a fairly big age difference if the latter were the case. Possible, but not probable. Also, the far right woman doesn't particularly resemble any of the others.
Doug