@ZioNemo - maybe you could use a Custom Column of type Comments
Comments are chunks of HTML so its possible to create a tabular form that uses Javascript, perhaps to add and delete rows etc.
Also, there's a widget in the Comments editor to insert links to say a website or a local file or folder, which could be within a calibre library.
Custom comments can be edited via the book list cells in a resizeable window, probably best to put them behind a suitable icon using Prefs->Look and Feel->Column icons, which is displayed only if the custom comment exists.
BR
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