By my definition, immediate family = one's parents, siblings, spouse(s) and children. Not grandparents/grandkids, cousins or in-laws. My grandmother and aunts are members of my parent's immediate family but not mine. My spouse's siblings are members of his immediate family but not mine. My sister's spouse is a member of her immediate family but not mine. My kids are members of my spouse's and my immediate family but not our parents' or siblings'.*
But we don't need to get bogged down with definitions of what does and doesn't constitute immediate family, and who should or shouldn't be in the "family" photos. That's up to the B&G to decide. Bottom line is, family or not, photos or no photos, Louise is not being very nice to Susan.
*Generic "my/mine" -- I don't have a spouse, kids or living grandparents.