I use mapped network drivers and the Subst command for making the base folders identical on separate PCs.
Locally on my main MC PC (the HTPC) I use Subst.
My music files are in reality in "D:\Mus\", video files are in "E:\Vid" and some other files are in "C:\Z\"
However, since I use a bat file that includes three Subst commands in my startup folder MC uses these locations:
X:\ (music)
Y:\ (videos)
Z:\ (etc)
The bat file is currently this:
SUBST X: D:\Mus
SUBST Y: E:\Vid
SUBST Z: C:\Z
I have shared the "D:\Mus", "E:\Vid" and "C:\Z" folders. On other PCs on my LAN I use mapped network drive letters (D:\Mus = X:, E:\Vid = Y:, C:\Z = Z:).
Since the filename paths are identical on all PCs I can restore the same MC library backup file on each PC.
When I am travelling I use an external USB2 drive with a laptop. The drive contains usually only the music files and I use a subst command for making the base path to be drive "X:". I can use the same library, the only difference is that the Y: and Z: drives are offline.