one family account for iphoto

I have read that this is possible, but I can't see where I can sign in with a different iCloud account for Photos.

Is this possible?

No, Photos will use the same iCloud account as your mail, notification, etc. You will not want to share his with the family members. Family sharing supports one shared photo stream for all family members but a shared iCloud Photo Library.

So Family Sharing is not really FAMILY sharing.

Sounds a bit dysfunctional to me.

So Family Sharing is not really FAMILY sharing.

Family Sharing is for sharing purchases but not for sharing data. You can share your purchased iTunes songs, videos, apps without having to use the same AppleID. So your kids can use the apps you purchased, but cannot access your account or read your mail, as they would be able to, if you had to use the same AppleID in all accounts.

Right now the only supported way to share a Photos library would be on an external drive, locally mounted, as described here for iPhoto: iPhoto: Sharing libraries among multiple users

Exactly my point in another thread (Re: "Family sharing" sharing iCloud storage?). Done right, Apple should have provided a way to securely keep my "private" photos in an exclusive file for my use only, but allow my family access to other files. As it now stands, I have to go in and select those photos I want to share and place them in a special "Family" folder. That's cumbersome when you have thousands of photos.

Sure, I could set up a folder file on an external drive locally, but my kids are in college, and they can't access this file without special software (which may not function correctly all of the time). As it stands, the current "Family Sharing" procedure is dysfunctional, like giving my son my credit card, but requiring him to ask permission before reading a book I bought.

Of course, I'm not even covering the inconvenience of buying extra storage space on iCloud but not being able to share that with my family.