Multiple Photo Libraries and iCloud

(This is not resolved - I could not undo the click...)

Well, I appreciate the effort of a reply - - but this is no more information than I found before I asked the question... I do a lot of research before attempting these types of things... And, since there is not a definitive answer about Apple's iCloud (not iCloud Photos) I will have to find another cloud to back up all my Photo Libraries... Thanks anyway...

Take a suggestion from Apple support? I see NO suggestion. If you are Apple's support-then, for the first time I am left stunned. My question was not answered. I was provided with links I had already found, prior to posting this query. The descriptions on those sites are vague and did not give me a definitive answer for my students.

I was hoping ALL my Photo Libraries would be backed up to the iCloud. Since, that does not appear to be the case - I will tell my students Apple's iCloud is for backing up ONLY the system Photo Library. My suggestion to them will be to do what I do - back all libraries to an external drive. And, if they want them in the cloud, they will need to find an alternative to the iCloud since it does not appear to do what we need it to do.

So, I don't mean to be rude, and this is why I usually don't do these types of things, but this has been more frustration than help... People attempting to answer a question, do not really read the question, which is obvious when reading replies...