That doesn’t sound like anything that’s already built in – most people would probably use a combination of the album, album artist and disc within the album – but there’s definitely nothing keeping you from adding a new field to your files. I do it myself, for a different purpose. If you don’t already know how, you can type whatever you want into the Add New Tag dialog; it doesn’t have to match anything in the dropdown list, but it won’t save between sessions, so make sure it’s not too difficult to type.
What @InvisibleMan78’s getting at, though, is that Picard saves custom fields like that in such a way that not every program shows them. If whatever you use besides Picard lets you type in arbitrary field names as well, then you won’t have any problem, but if you’re using Windows’ new Groove player or something else with a static interface, then you won’t see that data.