Below is an alternate version of the photo. Charlie, Oona & the kids are all "reading" from My Autobiography which was published the same year.
I believe Oona is lying on the same couch in the photo below, which is from Jerry Epstein's book Remembering Charlie. Jerry claims this is the couch that was featured in City Lights. Charlie liked the couch and kept it in his home in Switzerland (it appears to have been reupholstered at some point).