I have a main Windows 10 server where all my comics are stored. I access the yacreaderlibrary stored there from my client PC and the yacreader app on my ipad. My son also accesses the library from his PC. This is not ideal as things like current reading positions and favourites assume a single user.

As far as I'm aware YacReaderLibrary doesnt appear to support multiple users or separate user libraries without having multiple copies of the entire comics folder. But you can have separate library folders which contains a hard link to the actual comics folder. If there's a better way of doing this then please let me know.

So to have individual user libraries I did this:

On the comics server PC
comics folder:- f:\Comics [which will probably contain subfolders, ie. \Marvel, \DC, \Image etc...]

library folders:-
f:\yaclibraries\DadsLib
f:\yaclibraries\Kid1Lib

Using command prompt with admin privileges create a hardlink to the comics folder in each library folder:-
mklink /j "f:\yaclibraries\DadsLib\Comics" "f:\Comics"
mklink /j "f:\yaclibraries\Kid1Lib\Comics" "f:\Comics"

Libraries can be added in the yacreaderlibrary app (on the server) as usual by clicking the libraries + icon and choosing the relevant folders:-
f:\yaclibraries\DadsLib
f:\yaclibraries\Kid1Lib

Optionally to save a little space you can also have hardlinks to the covers thumbnails folder:-
mklink /j "f:\yaclibraries\DadsLib\.yacreaderlibrary\covers" "f:\Comics\yaccovers"
mklink /j "f:\yaclibraries\Kid1Lib\.yacreaderlibrary\covers" "f:\Comics\yaccovers"

On the client machines in the yacreaderlibrary app click the 'open existing library' icon and browse to the previously created libraries on the networked server, ie. DadsLib or Kid1Lib.

Relevant features like favourites and current reading positions will now be saved to each individual library.

Any modifications to the actual comics folder will need the libraries updating in the yacreaderlibrary app by right clicking the library name.